THE  INVESTIGATION  OF  CERTAIN  TYPES  OF 
SOUTH  AFRICAN  COALS,  WITH  SPECIAL  REF- 
ERENCE TO  THEIR  HIGH  NITROGEN  CONTENT 


By 

VERNON  BOSMAN 

A.  B.  University  of  the  Cape  of  Good  Hope,  South  Africa,  1917 
M.  A.  University  of  Cape  Town,  South  Africa,  1918 


THESIS 

SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS  FOR  THE 
DEGREE  OF  DOCTOR  OF  PHILOSOPHY  IN  CHEMISTRY  IN  THE 
GRADUATE  SCHOOL  OF  THE  UNIVERSITY  OF 
ILLINOIS,  1922 


URBANA,  ILLINOIS 


. 


THE  GRADUATE  SCHOOL 


Jtoy  10 


-192-2. 


I HEREBY  RECOMMEND  THAT  THE  THESIS  PREPARED  UNDER  MY 


SUPERVISION  BY- 


VERNON  B OSMAN 


ENTITLED 


OP  SOUTH  AFRICAN 


COALS,  WITH  SPECIAL  REFERENCE  TO  THEIR  HIGH  NITROGEN  CONTENT* 


BE  ACCEPTED  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR 


THE  DEGREE  OF 


by 


IaCAX^ 

P 


In  Charge  of  Thesis 


Head  of  Department 


*Required  for  doctor’s  degree  but  not  for  master’s 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/investigationofcOObosm 


ACKIIOY/LEDGgMSIIT 

The  author  wishes  to  thank  Professor  S.  W.  Parr 
tor  his  kind  assistance  and  advice  in  compiling 
this  thesis. 


TABLE  OF  CONTENTS 


I. 

Introduction 

1 

II. 

Historical 

The  distribution  of  nitrogen  in  the  distill 
of  coal  at  higher  temperatures 

ation  4. 

The  constitution  of  coal 

8. 

III. 

The  coals  studied 

Geography 

17. 

Analytical  data 

18.  | 

IV. 

The  nitrogen  in  coals 

Theoretical  considerations 

25. 

The  distribution  of  nitrogen  at  lower 
temperatures 

27, 

Conclusions 

28. 

The  action  of  chemical  reagents 

53. 

Hydrolysing  agents 

53. 

The  determination  of  NH3  nitrogen 

55. 

The  action  of  selenium  oxychloride 

60 . 

The  action  of  strong  reducing  agents 

62. 

66 

V. 

General  Summary  < and  Conclusions 
regarding  the  nitrogen  in  coal 

VI. 

Bibliography 

70 

VII. 

Vita. 

75  ! 

; 

' 


. 


> 


INTRODUCTION 


The  basis  of  this  work  is  an  investigation  oi  certain 
types  of  South  African  coals,  planned  with  a view  to  obtaining 
a more  fundamental  knowledge  of  the  form  in  which  nitrogen 
exists  in  coals.  Almost  all  the  coals  used  may  be  looked  upon 
as  high  nitrogen  coals,  five  of  them  containing  an  average 
amount  of  over  2 per  cent,  as  compared  with  an  average  of  1 
to  1.5  per  cent  in  American  coals. 

In  modern  industry  the  greatest  efforts  for  improve- 
ment have  been  in  the  direction  of  a thorough  system  of  uti- 
lising by-products.  The  scientific  status  of  an  industry  may 
very  often  be  determined  by  the  way  in  which  it  prevents  wast9 
in  all  directions.  As  an  example  of  this  kind  the  by-product 
coke  industry  is  no  exception.  It  fails,  however,  in  one 
respect,  namely  to  recover  the  maximum  amount  of  nitrogen  from 
the  coal. 

In  the  destructive  distillation  of  coal  on  a large 
scale,  not  more  than  15  per  cent  of  the  nitrogen  is  obtained 
as  ammonia,  while  50  to  60  per  cent  remains  behind  in  the  coke. 
Attempts  to  recover  this  nitrogen  from  the  coke  have  only 
succeeded  in  cases  of  special  treatment,  such  as  the  action 
of  steam  in  the  Mond  process,  or  the  addition  of  lime  to  the 
coal.  In  the  first  of  these  processes  60  to  70  per  cent  of 


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-3- 

the  nitrogen  in  the  coal  is  obtained  as  ammonia,  and  the  rest 
as  free  nitrogen  gas  arising  from  the  dissociation  of  ammonia. 
But  special  treatment  of  this  nature  destroys  the  coke  and 
acts  detrimentally  on  other  by-products.  For  this  reason  it 
is  not  always  economical.  We  must,  therefore,  resort  to  other 
means' — to  a process  which  would  increase  the  yield  of  ammonia 
without  affecting  the  remaining  by-products,  and,  at  the  same 
time  keep  the  total  cost  more  or  less  constant. 

A fundamental  study  of  the  nitrogen  in  coal  would 
add  materially  to  any  solution  of  our  problem,  and  would  bring 
us  to  a point  where  further  investigation  should  not  be 
difficult.  At  the  same  time  a study  of  the  nitrogen  would 
probably  throw  some  light  on  the  constitution  of  coal--  a 
subject  of  great  scientific  interest  and  importance. 

Importance  of  the  Problem. 

Fixed  nitrogen  in  the  form  of  ammonia  or  ammonium 

salts  or  combined  with  carbon  has  two  main  sources  through 

on 

which  it  finds  its  way  /to  the  markets  of  the  world.  One  of 
these  is  from  the  atmosphere  and  the  other  from  coal.  Today 
it  is  uncertain  which  of  these  two  sources  is  the  more  im- 
portant. Both  have  their  advantages,  but  the  disadvantages 
of  the  former — the  heavy  initial  cost,  and  the  uncertainty 


-3- 

and  complexity  of  the  process  as  a whole—  encourage  us  to 
believe,  that,  for  a long  time  to  come,  our  chief  source  for 
ammonia  will  be  from  coal.  In  the  United  States  alone  the 
total  reserves  of  nitrogen  in  coal  are  calculated  at  31,000,000, 
000  tons  (13), 

Explosives  and  fertilisers—  these  two  uses  alone  — 
the  one  largely  for  the  destruction  and  the  other  for  the 
maintai nance  of  life — have  made  this  problem  an  important  one. 
For  the  last  twenty  years  or  more,  we  have  listened  to  warn- 
ings, that  the  world  is  in  danger  of  starvation.  However  true 
these  warnings  may  have  been,  and  however  well  they  may  have 
been  met  by  scientific  progress,  the  danger  still  remains  acute. 
Although  there  has  been  a sudden  drop  in  the  output  of  explo- 
sives during  the  last  few  years,  the  demand  for  fixed  nitrogen 
is  greater  than  it  has  ever  been  in  normal  times.  This  is 
due  to  the  fact  that  during  the  wax,  much  of  the  nitrogen  which 
should  have  been  used  for  fertiliser  was  used  for  explosives, 
with  the  result  that  the  soild  suffered  and  the  human  fo^d 
supply  decreased  by  as  much  as  40  per  cent  in  some  European 
countries.  This  deficiency  has  now  to  be  met  or  the  world 
will  soon  be  underfed.  The  challenge  forms  one  of  the  most 
important  and  far  reaching  problems  with  which  the  chemist 
has  to  deal. 


■ 


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■ 


■ 


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-4- 


Latest  statistics  (49)  show  that  the  total  annual 
output  of  ammonium  sulphate  in  the  United  States  from  by- 
product coke  industries  amounted  to  935,000,000  pounds, due 
to  the  carbonization  of  44,324,000  tons  of  coal.  This  quantity 
of  ammonium  sulphate  is  equivalent  to  21.2  pounds  per  ton. 
Assuming  an  average  of  1.5  per  cent  of  the  nitrogen  in  the 
coal  used,  approximately  15  per  cent  of  the  nitrogen  in  the 
coal  was,  therefore,  recovered.  Now  if  the  efficiency  of  the 
process  could  be  raised  to  100  per  cent,  an  amount  of  approxi- 
mately 6,230,000,000  pounds  of  ammonium  sulphate  would  be 
obtained  from  the  same  amount  of  coal. 

Such  a condition  would  lower  the  price  appreciably 
and  nitrogen  fertilisers  will  be  brought  within  general  reach. 
One  of  the  most  pressing  problems  of  modern  agriculture  would 
thus  be  solved. 


HISTORICAL 

A.  On  the  Nitrogen  Content  of  Coal  and 

The  Distribution  on  Distillation. 

As  early  as  1844  Swindells  (l)  believing  that  coke 
acted  as  a sort  of  catalyst  in  distillation  processes, 
suggested  a method  of  preparing  ammonia  on  a large  scale  by 
passing  nitrogen,  nitric  oxides  and  steam  over  red  hot  coke. 


-5- 


Some  twenty  years  later  Berthelot  (2)  tried,  the  preparation  of 
hydrocyanic  acid  from  acetylene  and  nitrogen  in  the  same  way. 
Seeing  that  in  the  distillation  of  coal  quite  50  per  cent  of 
the  nitrogen  remains  behind  in  a form  which  is  decomposed  by 
steam,  it  is  likely  that  the  respective  yields  obtained  in 
these  experiments  resulted  from  this  origin. 

Henin  in  1382  (3)  was  further  attracted  by  the  subject 
and  arrived  at  conclusions  which  led  Mayer  and  Altmayer  (4)  to 
make  a thorough  investigation  of  the  effect  of  steam  on  the 
yield  of  ammonia  at  different  intervals  of  time  between  the 
temperatures  of  600°  and  900°.  tBeyfound  that  a maximum  yield 
of  62.7  per  cent  of  ammonia  was  obtained  at  800°. 

A little  later  James  McLeod  (5)  made  an  extensive 
study  of  the  behaviour  and  distribution  of  nitrogen  in  the 
distillation  of  coals.  He  concluded  that  at  the  temperature 
at  which  the  gases  are  evolved,  a part  of  the  nitrogen,  which 
is  liberated  entirely  as  free  nitrogen,  combines  with  hydrogen 
to  form  ammonia,  a part  with  carbon  and  hydrogen  to  form  cyanogen 
and  pyridine  and  a part  remains  as  free  nitrogen.  In  distil- 
lation experiments  in  which  227  to  413  tons  of  coal  were 
utilised,  McLeod  was  able  to  recover  as  much  as  17  per  cent  of 
the  nitrogen  as  ammonia  and  states  that  this  figure  depends  on 
certain  factors,  such  as  moisture  in,  and  the  physical 
condition  of,  the  coal.  Andrew  Short  (o)  in  a later  article 


‘ 


. 

. 


~ i 


-6- 

summarises  a whole  series  of  results  obtained  in  this  way,  as 
follows: — 


Distribution 
of  nitrogen 

Foster 

Knoblauch 

McLeod 

Short 

as 

ammonia 

14.5 

12.14 

17.1 

15 . 16 

as 

cyanogen 

1,56 

2 

1.2 

.43 

in 

the  coke 

48.68 

50 

58 

43.31 

in 

the  tar 

5.9 

2*98 

in 

the  gas 

35.26 

3C 

19.5 

37.12 

In  1911  W older eck  (7)  applied  these  methods  using 
peat  instead  of  coal  with  a view  to  obtaining  the  nitrogen  in 
the  form  of  ammonia. 

In  1914  0,  Simmersback  (8)  carried  out  a series  of 
investigations  regarding  the  relative  amounts  of  ammonia  and 
hydrocyanic  acid  at  temperatures  between  800°  and  900°  and 
showed  the  effect  of  steam  on  the  respective  yields.  J.  H?.  Cobb 
in  similar  experiments  found  that  by  removing  the  ammonia 
immediately  in  a distillation  process  carried  out  in  the  lab- 
oratory, a yield  of  22.5  per  cent  of  the  nitrogen  could  be 
obtained.  He  further  treated  the  coke  with  steam  and  obtained 
60  to  70  per  cent  of  the  nitrogen  as  ammonia—  the  conditions 
found  in  the  Mond  process. 

In  these  experiments  the  ammonia  yield  rapidly 
decreases  as  the  temperature  rises  above  800°  C,  due  to 


-7- 


dissociation  of  ammonia  at  these  temperatures.  Both  Simmer s- 
back  and  Cobb  conclude  that  the  nitrogen  comes  off  in  the  form 
of  ammonia,  rather  than  as  nitrogen  as  McLeod  suggests. 

In  1915  Terres  (13)  in  attempting  to  determine 
directly  the  form  in  which  the  nitrogen  exists  in  coal,  sub- 
jected a number  of  organic  compounds  with  nitrogen  linkages 
to  dry  distillation.  Such  compounds  as  gly cocoll,  asp ar agin, 
aloumin,  animal  glue,  pyridin,  azo benzol,  hy dr azobenzol, 
phenyl  isocyanate,  nitrobenzol  were  taken.  It  was  found  that 
only  those  substances  with  amino  and  substituted  amino  groupings 
gave  ammonia.  He,  therefore,  concludes  that  the  nitrogen  has 
an  "albuminous  mother  substance"  for  its  origin. 

In  1320  Glund  and  Breuer  (15)  worked  on  a gas  coal 
of  nitrogen  content  equal  to  1.86  per  cent  and  subjected  it 
to  low  temperature  distillation  in  a revolving  cylindrical 
retort.  He  found  that  66  per  cent  of  the  nitrogen  remained 
in  the  semi-coke  and  only  1.8  per  cent  of  the  nitrogen  was 
liberated  as  ammonia,  When  the  semi-coke  was  heated  a further 
16  per  cent  was  liberated,  thus  bringing  the  total  yield  of 
ammonia  to  17.8  per  cent. 

In  an  unpublished  thesis  (l6a)  by  Chiles  (1920)  the 
author  attempted  to  determine  actually  what  changes  occur  in 
the  nitrogen  molecule  during  the  coking  of  coal.  Attempts 
were  m^de  to  prepare  synthetically  the  same  compound  as  it 


-8- 


exists  in  coal  by  fusing  chemically  pure  carbon  obtained  from 
sugar  and  protein  substances.  No  definite  conclusions  were 
drawn,  but  results  seemed  to  indicate  the  presence  of  nitrides, 
or  direct  combination  of  carbon  and  nitrogen. 

« In  1S21  Monkhouse  and  Cobb  (16)  determined  the  effect 

of  hydrogen  and  nitrogen  alone,  and  in  the  presence  of  steam, 
on  coke  residues  prepared  at  500°,  800°,  and  1100°  C,  34.24 
per  cent  of  the  nitrogen  of  the  coke  was  obtained  with  500°  C 
coke  using  hydrogen  gas.  This  was  the  highest  yield  obtained. 

B.  On  the  Constitution  of  Coal. 

Running  almost  parallel  with  these  results  is  to  be 
found  a series  of  researches  carried  on  with  a view  to  obtaining 
a more  fundamental  idea  of  the  constitution  of  coal.  A determi- 
nation of  the  form  of  nitrogen  in  coal  would  be  a step  in  this 
direction.  For  this  reason  these  researches  have  been  described, 
In  this  work  three  general  methods  have  been  uni- 
versally employed/  l)  that  of  selective  solvents  (2)  microscopic 
investigations  and  fe)  distillation  processes. 

The  first  work  on  the  use  of  solvents  seems  to  have 
been  done  by  Dr  Smythe  (21)  at  Gottingen,  and  was  published 
in  a report  to  the  commissioners  of  the  1851  exhibition.  He 
used  a Cologne  coal  and  classified  the  following  solvents  in 
order  of  their  extractive  ability ' — benzene  3 per  cent 


. 

. 

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■ 


, 


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-9- 


chloroforin  1.8  per  cent,  ethyl  alcohol  2.4  per  cent,  ether, 
petroleum  ether  and  acetone — the  latter  three  dissolving  out 
a very  small  portion  of  the  coal.  In  all  these  extracts  , 
except  that  from  alcohol,  nitrogen  is  reported  absent. 

In  1879  Guignet  ( 1 7)  tried  the  action  of  phenol 
on  coal,  and  extracted  4 per  cent  of  the  coal.  He  then  tried 
the  action  of  nitric  acid  on  the  residue  and  extract.  This 
work  was  followed  up  by  Friswell  (18),  who  compared  the  action 
of  nitric  acid  on  graphite  and  coal  respectively.  With  coal 
he  obtained  a crystalline  product  which  he  believed  to  be  a 
nitro  compound,  similar  to  nitrocellulose.  From  90  grams  of 
a bituminous  coal,  finely  ground,  a residue  of  12.5  grams  was 
obtained. 

About  the  same  time  Smith  (19)  in  trying  the  action 
of  benzene  on  coal,  found  that  with  a certain  Japanese  coal  an 
extract  as  high  as  10  per  cent  was  obtained.  Smith  points  out 
the  unique  nature  of  this  coal,  and  goes  a step  further  in  a 
theory,  in  which  he  compares  the  origin  of  coal  with  that  of 
petroleum.  He  suggests  that  the  anthracite  coal  of  Penn- 
sylvania was  probably  at  one  time  of  its  formation  a bituminous 
coal  similar  to  the  one  of  Japan  on  which  he  worked,  but  owing 
to  pressure,  temperature  and  other  physical  phenomena,  had 
been  deprived  of  its  titumin  which  nowadays  is  being  brought 
to  the  surface  in  the  form  of  petroleum.  Regarding  the  nitrogen 


-10- 


in  the  coal.  Smith  seems  to  think  that  a high  nitrogen  content 
should  predict  animal  origin  and  substantiates  his  theory  by 
comparing  the  nitrogen  content  of  tar  from  wood  and  from  bone 
respectively. 

Following  these  experiments  work  of  Dr.  Smythe  (21) 
is  again  referred  to,  in  which  he  attacked  coal  with  dilute 
hydrochloric  acid  and  potassium  chlorate.  Thirty  to  35  per  cent 
of  the  coal  was  then  found  to  be  soluole  in  alcohol  and  acetone. 

By  extraction  with  benzene  he  was  able  to  separate  a number  of 
substances  containing  chlorine  and  a high  percentage  of  oxygen. 

Thus  C^oH-gClsOlC  and  c 35H jg01 4.0 20  were  recognised.  Anderson 

and  Roberts  (22)  took  up  the  work  from  here  and  extracted  an 
El  coal,  which  had  been  previously  oxidised  by  atmosphere  oxygen 
and  by  dilute  HN03,  with  potassium  hydroxide.  They  were  able 
by  this  means  to  extract  a number  of  acid  substances  believed  to 
be  derivatives  of  humic  acid.  Finally  they  conclude  that  the 
nitrogen,  or  nitrogen  containing  substances,  in  the  coal  have 
absolutely  nothing  to  do  with  the  coking  properties  of  the  coal. 
They  believe  that  the  coking  property  of  coal  is  due  to  the  ease 
with  which  certain  substances  in  the  coal  will  volatilize  or 
decompose,  and  that  a considerable  portion  of  the  organic  matter 
in  coal  consists  of  a complex  compound  comparatively  rich  in 
nitrogen,  and  containing  sulphur  as  well.  In  addition  to  these, 
resinous  material  is  always  present  to  a small,  but  fairly  constant 


-11- 


extent.  They  state  that  "the  nitrogenous  bodies  obviously 
owe  their  origin  to  the  proteid  substances  of  the  vegetable 
matter  from  which  the  coal  was  formed". 

Donat h and  Margosches  (24)  added  powdered  permanganate 
to  their  alkali  solvent  and  arrived  at  results  which  strengthened 
the  view  that  when  oxidised,  coal  yields  acid  substances, 
resembling  humic  acids. 

In  1901  Baker  (23)  tried  the  action  of  pyridin  on 
coal.  Donath  (25)  a little  later  carried  the  study  further 
on  a German  coal.  These  results  were  followed  by  a series  of 
experiments  by  Bedson  (26)  on  gas  coals.  Twenty-four  to  65 
per  cent  of  pyridin  soluble  material  was  obtained.  He  suggested 
that  the  pyridin  extract  might  te  related  to  the  volatile  matter 
in  the  coal,  but  this  theory  was  afterwards  disproved.  He  also 
applied  different  organic  solvents  to  extracts  and  residue  and 
obtained  interesting  results,  though  no  definite  conclusions. 

In  1911  Lewes  (28)  continued  the  work  and  arrived  at 
interesting  conclusions  regarding  the  coking  properties  of  the 
residue  and  extract.  He  explains  the  retention  of  the  coking 
properties  of  some  coals  by  assuming  the  presence  of  a resinic 
body  not  soluble  in  pyridin.  He  further  noticed  that  the 
percentage  of  volatile  matter  of  certain  coals  had  increased 
after  extraction  and  concluded  that  some  of  the  pyridin  was 
held  back  ty  the  coal  to  form  a compound  with  the  insoluble 


-12- 


part.  Lewes  points  out  that  pyridin  is,  therefore,  an  unsuitable 
solvent,  especially  for  nitrogen  investigations.  He  further 
states  that  the  resinous  bodies  in  coal  are  of  two  kinds  "the 
one  easily  oxidisable,  soluble  in  pyridin  and  saponifiable  by 
alkalies,  and  which  on  weathering  is  oxidised  into  humus  bodies 
with  the  evolution  of  water  and  carbon  dioxide,  and  the  other 
non  oxidisable,  not  saponified  by  alkalies,  and  forming  with 
pyridin  a compound  insoluble  in  excess  of  the  reagent;  and  this 
Class  may  be  the  hydro-carbons  from  decomposed  resins,  as  the 
residue  in  which  they  are  present  yields  rich  liquid  hydro- 
carbons, as  tar  and  pitch,  but  not  rich  in  gas." 

In  1911  Pictet  (29)  working  at  different  times  in 
conjunctions  with  Ramseyer,  B©uvier,  Labonchere,  Combes  and 
Kaiser,  started  on  a series  of  researches  which  gradually  de- 
veloped into  a very  interesting,  as  well  as  a useful  piece  of 
work.  These  investigators  attached  the  problem  from  two  angles. 
In  their  first  series  of  experiments  they  extracted  a "fat" 
coal  of  Montrambert  (Loire)  with  benzene.  The  distillate  was 
obtained  in  the  form  of  a tar,  which  was  fractionally  distilled 
into  a number  of  products,  which  the  authors  were  able  to 
identify.  Amongst  these  compounds  were  hexahydrof luerene , a 
number  of  hydro-carbons,  phenols  and  bases.  The  same  coal  was 
then  subjected  to  vacuum  distillation  up  to  a temperature  of 
450°  and  at  a pressure  of  13  to  15  mm.  The  tar  obtained  was 


* 

• 

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-13- 


found  to  be  similar  to  the  tar  obtained  in  the  first  case,  and 
these  in  turn  showed  marked  resemblances  to  the  fractions 
obtained  from  petroleum.  The  authors  finally  conclude  that 
the  coal  and  petroleum  have  similar  origins  (41).  These 
investigations  were  started  with  the  object  of  finding  out  the 
form  in  which  nitrogen  exists  in  coal,  but  no  conclusions  on 
this  point  were  drawn. 

About  the  same  time  that  these  researches  were  begun, 
Wheeler  together  with  Burgess  (30),  Jones  (35)  and  Clarke  (33) 
set  out  on  a thorough  investigation  on  the  solvent  action  of 
pyridin  on  coal  and  were  able  to  arrive  at  conclusions  on  'which 
a theory  was  based.  They  found  that  when  coal  was  extracted 
with  pyridin,  the  extract  contained  resinous  decomposition 
products  together  with  a substance  of  cellulosic  origin.  These 
two  substances  they  were  able  to  separate  by  means  of  chloroform. 
On  destructive  distillation  of  these  three  substances  they  found 
that  the  residue  yielded  chiefly  hydrogen,  while  the  pyridin 
soluble,  chloroform  insoluble  part,  yielded  chiefly  hydro-carbons. 
The  chloroform  soluble  part  of  the  extract  resembled  the  residue 
in  yielding  chiefly  hydrogen.  They  therefore  concluded  that 
coal  was  composed  of  two  parts  (l)  the  hydrogen  yielding  and 
(3)  the  paraffin  yielding  constituents.  They  further  illustrated 
their  results  by  analysing  the  gases  given  off  at  different 
temperatures  in  the  destructive  distillation  of  coal. 


. 


. 

'-A" 


* 


. 

■ 


-14- 


In  1912  Hoffman  and  Fraser  (31)  published  a paper 
on  "The  Constituents  of  Coal  Soluble  in  Phenol".  Illinois 
coal  from  Franklin  County  was  taken  and  it  was  found  that 
10.8?  per  cent  calculated  on  the  moisture  and  ash  free  basis 
was  soluble.  By  the  use  of  sodium  hydroxide  and  other  organic 
solvents  they  were  able  to  extract  certain  substances  out  of  the 
coal  which  they  believed  to  be  pure.  Complete  analysis  of  these 
substances  were  given,  but  no  constitutional  formula  established. 

This  work  was  followed  up  by  Parr  and  Hadley  (34)  in 
a very  thorough  investigation  on  the  properties  of  the  residue 
and  extract,  using  phenol  as  solvent.  These  investigators 
believe  that  phenol  is  the  best  solvent  to  use  as  it  undergoes 
decomposition  only  to  a very  slight  degree  and  does  not  effect 
the  coal  as  does  pyridin.  Both  the  residue  and  extract  were 
analysed  and  examined  in  regard  to  their  resistance  to  air  and 
their  coking  properties.  They  find  that  the  nitrogen  divides 
itself  more  or  less  evenly  between  the  residue  and  extract. 

Porter  and  Taylor  (36),  working  on  the  volatile  products 
of  coal,  carried  out  investigations  on  four  coals,  which  unfor- 
tunately had  been  weathered.  They  arrived  at  results  on  the 
constitution  of  coal  which  were  opposed  to  those  of  Wheeler  and 
state  that  the  "cellulosic"  material  in  the  coal  is  first  d e- 
composed  on  exposure  to  heat. 


Microscopically  some  very  brilliant  researches  have 


-15- 


been  carried  out  on  ccal,  which  throw  a good  deal  of  light  on 
its  origin  and  constitution.  Amongst  the  foremost  workers  in 
this  field  may  be  mentioned  Thiessen  (59),  White  (58),  Stopes 
and  Wheeler  (5?). 

In  the  last  four  or  five  years  a great  deal  of  inves- 
tigation has  been  done  on  the  action  of  chemical  reagents  on 
coal  which  has  produced  interesting  though  not  conclusive  results. 
This  work  has  mostly  origined  from  German  chemists,  and  unfortu- 
nately could  not  be  obtained  in  the  original  articles  by  the 
writer. 

Thus  Keller,  Hilpert  and  Lepsius  (40)  treated  a 
bituminous  coal  with  acetic  anlydride  and  zinc  chloride  in  a 
sealed  tube  and  then  subjected  the  residue  with  nitric  acid.  The 
content  of  nitrogen  increased  from  1.8  per  cent  to  8 per  cent. 

This  substance  they  called  "nitrc-coal".  They  found  it  insoluble 
in  acetone,  acetic  acid  and  benzene.  The  extract  resembled  the 
residue  when  these  were  subjected  to  destructive  distillation, 
and  was  soluble  in  alkalies.  They  failed  to  prepare  sulphuric 
acid  derivatives  and  suggested  the  absence  of  aromatic  hydro- 
carbons as  a result. 

Fisher  and  Groppel  (41)  about  the  same  time  tried  the 
effect  of  pre-heating  the  coal  and  thereby  increasing  the  extracts 

obtained  by  solvents. 

With  Niggerman  (42),  Fisher  tried  the  effect  of  ozone 


. 


, 


. 


. 

. 

, 

. 

. 


. 


-16- 


on  coal,  and  found  that  the  humic  acid  substances  were  rendered 
soluble- — the  amount  being  inversely  proportional  to  the  coking 
properties  of  the  coal.  The  ozonised  product  was  dried  at  110° 
and  contained  3 per  cent  H,  50  per  cent  C,  .8  per  cent  S and 
only  traces  of  nitrogen--the  original  coal  containing  5 per  cent 
H,  84  per  cent  C,  .9  per  cent  S.  A little  later  Fisher  and 
Tropsch  (47)  tried  the  same  reaction  in  a non  aqueous  media,  but 
could  observe  no  changes  in  the  reaction.  The  same  authors  also 
tried  the  effect  of  hydrogen  iodide  (47)  on  coal  and  found  that 
coals  of  early  origin  were  attacked  sooner  than  those  of  later 
origin.  The  amount  of  extract  obtained  with  chloroform  after 
such  treatment  was  increased  from  3.7  per  cent  to  73  per  cent 
in  the  case  of  a cannel  coal. 

In  1921  F.  Fischer  and  Schrader  (48)  published  a 
paper  on  the  origin  and  chemical  structure  of  coal,  which  con- 
tained a number  of  new  ideas  and  new  theories,  not  the  least 
of  which  was  the  fact  that  they  question  all  previous  theories 
on  the  subject.  According  to  them  coal  originates  from  the 
lignin  in  the  plant  — the  cellulose  being  decomposed  by  bacterial 
action  in  the  early  stages  of  peat  formation,  with  the  formation 
of  C03  and  Ha0.  Lignin,  they  state,  has  an  aromatic  structure, 
with  acetyl  and  methoxyl  groups.  Thus  in  the  formation  of  peat 
the  methoxyl  groups  increase,  while  the  portion  soluble  in 
concentrated  hydrochloric  acid  decreases.  Finally  the  methoxyl 


. 

E ..-r  :c  ' v . o.  A *'  i---  •*>>«  ft 


. 


. 


. 


. 


. 


-17- 


groups  axe  replaced  by  hydroxyl  groups  to  form  a compound 
identical  with  humic  acid.  Further  splitting  off  of  HSQ, 

C02  and  CH4  give  rise  to  lignite.  The  authors  quote  experi- 
mental evidence  in  proof  of  their  theory. 

Five  months  later  a further  article  appeared  in 
which  the  above  theory  received  severe  criticism  at  the  hands 
of  Klever,  Forschner,  Jonas  and  others.  The  question  still 
remains  unsettled. 

The  Coals  Studied. 

The  coals  which  formed  the  basis  of  the  study  described 
in  this  paper  came  from  South  Africa.  Fourteen  samples  from 
different  mines  were  sent  to  this  University  by  Mr.  P.  Wagener, 
Inspector  of  Mines  for  the  Union  of  South  Africa.  These  samples 
were  taken  according  to  standard  methods  and  were  received  in 
good  condition  in  well  sealed  tins.  Unfortunately  all  but  a few 
were  packed  in  the  finely  ground  condi tion — a condition  in  which 
weathering  is  most  effective.  No  attempts  were  made  to  investi- 
gate the  extent  of  weathering. 

The  coal  resources  of  the  Union  of  South  Africa  were 
estimated  in  1913  at  57,839  million  tons.  This  is  probably  a 
considerable  underestimate.  Between  1913  and  1S20  the  total 
output  of  the  Union  was  increased  by  45  per  cent,  it  being 
nearly  12  million  tons  for  1920. 


. 


. 


. 


. 


. 


. 

. 


. • 

. 

. 


-18- 


Alraost  all  the  coal  in  the  Union  comes  from  two  states, 
the  Transvaal  and  Natal — the  latter  coals  being  of  a slightly 
higher  quality.  The  position  of  these  fields  i3  shown  in  the 
map  in(Figure  I),  according  to  the  following  list. 

1.  Utrecht  Collieries — Natal 

2.  Cambria  Collierie s— Dannhouse  Natal 

3.  South  African  Northfield  Collieries—Glencoe  Natal 

4.  Navigation  Collieries--Natal 

5.  Transvaal  and  Delegoa  Bay--Witbank 

6.  Clydesdale  Collieries 

7.  Cassel  Coal  Coy — Blackhill 

8.  Middelburg  Steam  Coal  & Coke  Coy 

9.  Coronation  Collieries 

10.  Emyati  Collieries — Langkjans — Natal 

11.  Uitspan  Collieries — W itbank 

12.  Clydesdale  Collieries 

13.  Tavistock  Coal  and  Coke  Co-r-W itbank 

14.  African  Freehold  Coal  Lands  Ltd. 

Vaalbank,  Middelburg 

Experime ntal . 

In  order  to  get  a thorough  idea  of  the  nature  of  these 
coals  complete  analyses  were  made.  The  methods  used  were  those 
described  in  "Gas  and  Fuel  Analysis"  by  White,  "Water  and  Fuel 
Analysis"  by  Parr  and  "Methods  of  Analysing  Coal  and  Coke"  by 
Stanton  and  Fildner. 

Total  carbon  was  determined  by  the  Parr"total  carbon" 
apparatus.  Oxygen  and  hydrogen  were  calculated  from  the  Dulong 
formula.  Heat  values  were  made  by  the  Parr  Adiabatic  Calorimeter. 


* 


■ 


' 


* 


. 

I , 


Coalfields. 


-20- 

The  Kjeldahl  Gunning  method  was  employed  in  all 
nitrogen  determinations.  One  gramme  of  coal  is  placed  in  a 
500  cc  Kjeldahl  flask,  and  .5  grams  of  KHS04,  .5  grams  of  Hg. 
and  30  oc  of  concentrated  sulphuric  acid  added.  The  mixture  is 
digested  for  three  to  four  hours  and  after  removing  the  Hg  with 
K2S  is  finally  distilled  in  the  presence  of  NaOH  into  standard 
H2S04. 

In  the  case  of  coke  it  is  advisable  to  take  .5  grams 
of  the  material,  digest  for  three  hours  then  add  a few  crystals 
of  KMn04  and  finally  digest  for  three  hours  longer.  In  each 
set  of  determinations  blanks  were  made  and  subtracted  from  the 
total  amount. 

Table  1 shows  the  proximate  analyses,  calculated  to 

the  moisture  and  ash  free  basis;  Table  2 shows  the  ultimate 

analyses  and  Table  3 their  classification.  In  order  to  get  a 

better  understanding  of  their  classification,  each  coal  was 

plotted  graphically  (Figure  II)  according  to  the  classification 

of  Parr  and  Vliet.  In  this  classification  the  unit  volatile 

matter  is  plotted  against  the  unit  B$.U  value  of  the  coal.  Unit 

volatile  matter  is  defined  as  the  volatile  matter  on  the  pure 

coal  substance  and  is  calculated  from  the  following  formulas. 

unit  volatile  matter  (pure  coal)  = 100-  fixed  carbon  on  pure 

coal  basis 

fixed  carbon  (pure  coal)  = fixed  carbon  as  determined 

1-(1.0S  A - 1/ 2S  - 1/20S  - M) 

where  A=ash  content. 

S=sulphur  content 
M-moisture  content 


. 


. 


. 


* 


. 


. 


. 


. 


TABiiS  I SHOTOIG  PROXIMATE  ANALYSIS  OF  GOALS 


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Table  2 SHOWING  ULTIMATE  ANALYSIS  OF  COALS 


‘ & 

O H 

Location  «$  ,o  Ultimate  Analysis  Calorific  Value 

O P 

rQ  S 

c3 

Hi 


S. 

Ha 

C arb  on 

n2 

03  Calories  B.t, 

Utrecht  Coll. 
Natal 

1 

1.58 

4.45 

70.70 

2.12 

7.72 

6952 

12334 

Cambria  Coll. 
N at  al 

2 

1.67 

4.90 

75.93 

2.17 

5.66 

7616 

13707 

S. A , Northf ield  Coll. 
N at  al 

3 

1.71 

4.79 

77.33 

2.32 

4.97 

7726 

13917 

Navigation  Coll. 
N at  al 

4 

1.72 

4.64 

76.30 

2.17 

4.60 

7606 

13695 

Transvaal  & Dele  go a 
Bay.  Wit  bank  No.  8 

5 

1.24 

4.81 

69.33 

1.68 

8.20 

6900 

12421 

Clydesdale  Coll. 
Blackhill  No.  2 

6 

1.26 

4.22 

70.50 

1.62 

8.61 

6808 

12255 

Cassel  Coal  Coy 
Blackhill  No.  1 

7 

1.29 

4.46 

71.98 

1.68 

8.18 

7057 

12702 

Steam  Coal  & Coke 
Midaleburg 

8 

.87 

4.16 

67.45 

1.53 

8.07 

6558 

11805 

Coronation  Coll. 
No.  3 

9 

.88 

4.80 

68.18 

1.67 

9.27 

6787 

12119 

Emyati  Coll. 
N at  al 

10 

1.24 

4.54 

77.47 

2.11 

5.40 

7622 

13720 

Uitspan  Coll. 
Wit bank  No.  10 

11 

.84 

4.23 

68.43 

1.61 

8.43 

6645 

11960 

Clyde  sdale 
No,  2 

12 

1.40 

4.33 

69.86 

1.60 

8.61 

6797 

12232 

Tavistock  Coal  Coy 
Witbank  No.  6 

13 

1.39 

4.30 

71.  38 

1.75 

8.07 

6925 

12464 

African  Freehold 
Middle  burg 

14 

.42 

4.54 

70 . 38 

1.78 

9.72 

6885 

12392 

No.  11 


* 


-Si- 


Table  3 SHOWING  THE  CLASSIFICATION 

Vol.Mat. 


Locality 

L ab ' y 
No. 

Vol.Mat. 
(air  dried) 

Unit 

B.t .u. 

on 

Unit  coal 

Cambria  Coll. 
N at  al 

2 

28.04 

15351 

29.80 

Emyati  Coll. 
N at  al 

10 

23.70 

15271 

25.01 

S, A.Northf ield  Coll, 
Natal 

5 

23.10 

15421 

24.07 

Navigation  Coll. 
Natal 

4 

22.29 

15508 

2o . 50 

Transvaal  & Delegoa 
Bay.  Witbank  No.  8 

5 

33.41 

14805 

37,96 

Cassel  Coal  Coy 
Blackball  No.  1 

7 

29.98 

14803 

33.05 

Steam  Coal  & Coke 
Middle burg 

8 

27.99 

14767 

32.65 

Clydesdale  Coll. 
Blackhill  No.  2 

6 

28.28 

14409 

31.55 

Coronation  Coll. 
No.  3 

9 

27.56 

14426 

31.24 

Clydesdale 
No.  2 

12 

28.46 

14444 

31.88 

African  Freehold 
Coal  Coy.  Middle- 
burg  No.  11 

14 

29.16 

14425 

32.45 

Utrecht  Coll. 
Natal 

1 

25.93 

14442 

28.53 

Uitspan  Coll. 
Witbank  No.  10 

11 

25.47 

14550 

29.13 

Tavistock  Coal  Coy 
Witbank  No.  6 

13 

28.43 

14541 

31.47 

-25- 


The  Nitrogen  in  the  Coal. 

From  this  point  attempts  were  made  to  determine  in 
what  form  the  nitrogen  exists  in  coal.  For  this  purpose  two 
methods  of  attack  were  adopted  (l)  the  distillation  of  coal 
in  the  presence  of  carbon  dioxide  (2)  the  use  of  chemical  re- 
agents at  lower  temperatures.  According  to  a recent  thesis 
by  Ho^bart  (5?)  carbon  dioxide  does  not  affect  carbonization 
processes  in  any  way. 

Theoretical 

In  order  to  get  some  basis  upon  which  to  build,  it 
is  necessary  to  make  use  of  certain  theoretical  considerations 
regarding  the  origin  of  coal — theories  which,  hov/ever,  are  now 
widely  accepted  by  geologists  and  chemists. 

Thus  David  White  (38)  in  a very  extensive  and  thorough 
bulletin  on  "The  Origin  of  Coal",  and  later  Thiessen  and  White 
(3S)  on  the  ’’Structure  in  Paleozic  Bituminous  Coals”  claim  that 
the  decomposition  towards  the  formation  of  coal,  is  exposed  to 
two  fundamental  agencies  Q)  Biochemical  or  Bacterial  and  (2  )Dynamo- 
chemical . 

In  the  first  of  these  stages  the  formation  of  peat,  or 
its  equivalent  in  rank,  is  brought  about;  in  the  latter  the  peat 
is  exposed  to  the  action  of  pressure  and  temperature,  during 
which  process  a low  grade  lignite  is  formed.  Water  is  expressed, 
thereby  reducing  the  mass  by  as  much  as  three-fourths,  gases  axe 
expelled,  organic  compounds  are  further  broken  dov/n  and  finally 

oxygen,  nitrogen  and  hydrogen,  together  with  varying  amounts 
of  carbon  are  liberated. 


. 


. 


- 

. 


. 


-26- 


Furthermore  at  this  stage  we  assume  that  the  nitrogen 


in  coal  originates  from  the  protein  at  one  time  present  in  the 
plant  from  which  the  coal  was  formed.  Coming  from  the  plant  it 
is  certain  that  the  nitrogen  is  of  organic  and  not  of  inorganic 
origin.  It  is  true  that  certain  plants  contain  alkaloids,  in 
which  the  nitrogen  is  bound  differently  in  the  molecule  from 
protein,  but  it  is  not  likely  that  these  compounds  play  any 
part  in  coal  formation,  for  such  plants  are  not  common  and  are 
small  in  bulk.  All  writers  who  have  had  anything  to  do  with  the 
nitrogen  in  coal  have  believed  that  protein  is  its  true  origin. 


dilute  hydrochloric  acid,  readily  decompose.  This  has  been 
shown  by  Hlasiwetz  and  Haoerman  (50),  Kossel  (51),  Kutscher  (52), 
Emil  Fischer  (5b)  and  others.  Thus  when  proteins  are  hydrolysed 
in  the  laboratory  we  obtain  chiefly  as  decomposition  products 
the  following  groups  of  compounds: 

(1)  Amino  acids,  which  include  monamino  and  di amino 
carboxylic  acids,  eg:  Amino  acetic,  amino  valeric,  diamino 
propionic,  diamino  glutcefiiq. 

(2)  Acid  amides  eg:  acetamide. 

(b)  Heterocyclic  compounds  eg:  Histidine,  having  the  for- 


and  oxy prolin®. 

Now  v/hen  proteins  are  exposed  to  the  natural  agencies 
as  are  supposed  to  exist  in  the  formation  of  coal,  we  would 
expect  hydrolysis  brought  about  by  bacterial  action,  and  as  a 
result,  the  products  of  decomposition  would  be  brought  down  in 


Proteins  in  the  presence  of  hydrolysing  agents  such  as 


mula 


. 


-27- 

the  coal.  There  is,  however,  a possibility  for  chemical 
combination  to  take  place  with  other  organic  compounds  in  the 
plant  before  complete  hydrolysis  has  taken  place,  especially 
if  the  protein  is  protected  in  some  physical  way  by  the  plant 

tissue.  This  possibility  is  dealt  with  in  later  experiments 

sing 

which  determine  the  effect  of  hy dr oly /agents  on  the  nitrogen 
molecule  in  coal.  These  theoretical  considerations  form  the 
basis  of  the  work  which  is  to  follow. 

Experimental. 

A.  Distillation. 

In  the  first  series  of  experiments  a thorough  investi- 
gation was  made  of  the  behaviour  of  the  nitrogen  when  coal  is 
distilled  in  an  atmosphere  of  carbon  dioxide,  between  the 
temperatures  of  450°  and  600°  C.  These  temperatures  were  chosen 
because  it  was  found  that  below  450°  C the  quantities  of  tar 
and  ammonia  which  could  be  collected  from  100  grams  of  coal  wegg 
hardly  sufficient  to  enable  us  to  make  any  determinations.  On 
the  other  hand  at  600°  C the  gases  could  be  removed  before  any 
appreciable  decomposition  of  the  ammonia  or  tar  takes  place. 

In  the  distillation  of  coal  it  is  universally  known 
that  the  respective  yields  of  coke,  tar  and  gas  depend  upon  the 
conditions  of  the  process.  Such  factors,  for  instance,  as 
temperature,  pressure,  time  and  contact  surfaces  will  alter  the 
yields  in  appreciable  amounts.  Consequently  all  attempts  were 
made  to  keep  other  factors,  beside  the  temperature,  constant 
in  different  experiments. 

For  this  purpose  the  apparatus  was  used  as  is  shown  in 


. 


. 

. 

. 

-28- 


the  diagram  (Fig.  3)  100  grams  of  coal  in  the  finely  ground 
ccnditionwer e placed  in  A for  each  run.  By  lowering  F as  much 
of  the  air  is  withdrawn  from  the  apparatus  as  possible.  Carbon 
dioxide  is  then  passed  through  the  apparatus  through  the  tube 
C for  one-half  to  three  quarters  of  an  hour.  The  heating  is 
done  electre^Kfcically  and  the  temperature  kept  constant  during 
each  run  by  a series  of  resistances.  As  temperature  and  time 
are  important  factors  in  distillation  processes,  the  rate  of 
heating  of  the  furnace  is  shown  in  (Fig.  4)  . 

The  tar  collects  in  B,  and  the  gases,  after  being 
filtered  through  glass  wool  in  C,  pass  through  the  two  flasks  D, 
each  containing  about  100  cc  of  approximately  normal  sulphuric 
acid.  Finally  the  gas  is  collected  in  E under  reduced  pressure 
obtained  by  lowering  F to  the  same  extent  in  each  case. 

Four  coals  are  heated  in  this  way.  In  each  case  gases 
begin  to  come  off  as  soon  as  the  temperature  begins  to  rise. 

This  steady  evolution  of  gas  continues  throughout  the  experiment 
and  at  about  400°  C5  a further  decomposition  in  the  coal  is 
shown  in  the  appearance  of  tar.  The  coal  is  subjected  to  each 
temperature  for  periods  of  five  hours. 

The  ammonia  given  off  is  collected  very  efficiently 
in  the  two  conical  flasks  D of  150  cc  capacity.  The  contents 
of  the  flasks  are  finally  transferred  to  a measuring  flask  and 
made  up  to  200  cc.  Aliquot  parts  are  distilled  in  the  presence 
of  sodium  hydroxide  into  standard  acid  and  the  amount  of 
ammonia  thus  calculated. 

The  tar  and  water  given  off  are  collected  in  B,  A 


-29- 

separation  of  these  products  is  brought  about  by  the  centrifuge 
and  the  respective  quantities  measured. 

Analyses  of  the  gases  given  off  in  each  case  sho?»’ed 
small  percentages  of  nitrogen.  These  amounts  evidently  arose, 
partly  from  the  occluded  gases  which  are  always  present  in  coals 
and  partly  from  the  decomposition  of  ammonia.  The  amounts  were 
small  and  consequently  neglected  in  the  calculations. 

The  results  are  shown  in  tables  4 to  11.  In  tables 
12  to  15,  the  percentage  distribution  of  nitrogen  is  given  at 
each  temper ature.  In  these  cases  the  error,  that  i3  the  per- 
centage of  nitrogen  unaccounted  for,  is  given.  In  cases  where 
the  error  is  indicated  by  a positive  sign,  it  appears  that  the 
sum  total  per  cent  of  nitrogen  in  the  coke,  tar  and  ammonia  is 
more  than  in  the  original  coal.  In  other  cases  indicated  by  the 
minus  sign,  some  of  the  nitrogen  still  remains  unaccounted  for. 

The  discrepancy  may  be  due  to  inconsistencies  in  the  Kjeldahl- 
gunning  method  for  determining  nitrogen  in  coke.  Some  of  these 
errors  are  greater  than  experimental  error  would  warrant.  Yet 
considering  that  the  quantities  of  coal  and  coke  are  taken  to 
the  nearest  gramme,  on  the  whole  the  results  agree  remarkably  well], 
and  give  us  a very  excellent  idea  of  what  happens  to  the  nitrogen 
part  of  the  molecule  when  coal  is  distilled  between  these 
temperatures. 

These  results  are  explained  in  another  way  in  the 
diagrams  shown  in  Figures  5 to  13.  Here  we  have  endeavored  to 
show  the  behaviour  of  each  coal  separately  as  it  passes  from  one 
temperature  to  another.  Thus  Figures  5 to  8 show  the  respective 

amounts  of  volatile  matter,  tar,  ammonia  and  gas  of  each  coal  at 


o 

NO 


SHOWING  FURNACE  RISE  IN  TEMPERATURE  WITH  TIME 


-33- 


Table  4 


SHOWING 

ACTUAL  QUANTITIES 

GIVEN 

OFF  AT  450 

° c 

Experiment 

Number 

Amount  of 
coal  taken 
(gms) 

Coke 

Tax 

nh3 

Gas 

Ha0 

3 A 

100 

88 

3.23 

.0085 

6325 

3.3 

7 B 

100 

83 

5 

0070 

6150 

4.0 

11  C 

100 

87 

3.3 

0081 

5400 

4.5 

14  D 

100 

83 

3.10 

0010 

5700 

3.00 

Table  5 


SHOWING  ACTUAL  QUANTITIES  GIVEN  OFF  AT  500°  C 


Experiment 

Amount  of 

Coke 

Tar 

nh3 

Gas 

Ha0 

Number 

coal  taken 

3 E 

100 

87 

3 . 90 

.011 

8900 

3 ,5 

7 F 

100 

81 

5.6 

0075 

8400 

5.8 

11  G 

100 

86 

3.53 

0087 

7200 

5.8 

14  H 

100 

79 

6.00 

0021 

8000 

7 

-33- 


Table  6 


SHOEING  ACTUAL  QUANTITIES  GIVEN  OFF  AT  550°  C 


periment 

Number 

Amount  of 
coal  taken 
(gms) 

Coke 

3 I 

100 

64 

7 J 

100 

7S 

11  K 

100 

84 

14  L 

100 

78 

Tar  WH3  Gas  H80 


3. S3 

.054 

13S00 

3.5 

5.7 

.016 

9950 

o 

5.80 

.0088 

8450 

6 

6.30 

.016 

9400 

7 

Table  7 


SHOWING  ACTUAL  QUANTITIES  GIVEN  OFF  AT  600°  C 


Experiment 

Number 

Amount  of 
coal  taken 
(gms) 

Coke 

Tax 

nh3 

Gas 

H20 

5 M 

100 

82.5 

4.10 

056 

15000 

4.5 

7 N 

100 

77 

5.7 

034 

11900 

6 

11  0 

100 

61 

3.82 

023 

10600 

6 

14  P 

100 

76 

6.46 

043 

11650 

7 

-34- 

Table  8 

SHOWING  PERCENTAGE  OF  NITROGEN  IN  PRODUCTS  GIVEN 


OFF 

AT  450 

° C 

Experiment 

Number 

Coal 

Coke 

Tar 

nh3 

Gas 

3 A 

2 « 0'& 

2.70 

.85 

0067 

— f 

7 B 

1.68 

2.03 

.95 

0058 

1.5 

11  C 

1.61 

1.85 

.92 

0067 

2.8 

14  D 

1.78 

2.07 

.60 

0008 

1.9 

Table  9 

SHOWING  PERCENTAGE  OF  NITROGEN  IN  PRODUCTS  GIVEN 

OFF  AT  500°  C 


Experiment 

Number 

Coal 

Coke 

Tar 

NHg 

Gas 

3 E 

2.32 

2.68 

.95 

.009 

2.5 

7 F 

1.68 

1.89 

.99 

0062 

4 

11  G 

1.31 

1.80 

.97 

0072 

2.8 

14  H 

1.78 

2.07 

.92 

0017 

2.3 

Table  12 


-36- 


SHOWING 

PERCENTAGE  DISTRIBUTION 

OF  NITROGEN  AT 

o 

0 

O 

9 

3 

7 

11 

14 

$ f 

distrib. 

jo  jo  distrib. 

jo  jo  distrib.  jo  jo 

distri 

Coke 

2.38 

28.60 

1.68  93.94 

1.61  97.75 

1.72 

98.85 

Tax 

.027 

1.12 

.047  2.71 

.03  1.82 

.019 

1.09 

nh3 

0067 

.27 

.0058  .34 

.0067  .41 

0008 

.05 

Error 

+09 

+ .05 

+ .034 

- 

.04 

Table  15 

SHOWING  PERCENT AGE  DISTRIBUT I ON  OF  NI TROGEN  AT  500°  C 


* 


jo  distrib. 


7 11  14 

jo  j>  distrib.  jo  jo  distrib.  jo  jo  distr 


Coke 

2.34 

28.07 

1.53 

96.23 

1.55 

97.48  1.64 

96.47 

Tar 

.037 

1.80 

.055 

3.46 

.034 

2.14  .055 

0 . 23 

nh3 

.009 

.38 

.0062 

• 

CO 

.0072 

.45  .0017 

.10 

Error 

+ .07 

1 

• 

o 

CO 

.02 

00 

0 

• 

1 

-37- 


Table  14 

SHOWING  PERCENTAGE  DISTRIBUTION  OF  NITROGEN  AT  550°  C 


3 

7 

11  14 

%distrib. 

* 

^distnb.  fo  distrib 

f-distr  ib 

Coke 

2.24 

96.13 

1.53 

95.62  1.55  96.88  1.64 

95.57 

Tar 

.043 

1.84 

.057 

3.55  .041  2.56  .062 

3.61 

NHS 

.045 

1.93 

.016 

.9  .0073  .46  .014 

.82 

Error 

+ 

.01 

-.08  -.01 

CD 

O 

• 

0 

Table  15 

SHOWING  PERCENTAGE  DISTRIBUTION  OF  NITROGEN  AT  600°  C 


3 

7 

11 

14 

i° 

fodistrib  fo 

fodistr  ib 

* 

fodistr  ib. 

1o 

fcdistrib 

Coke 

2.23 

96.12  1.47 

94.53  1 

.54 

96.25  1 

.61 

94.16 

Tar 

.045 

1.94  .057 

3.65 

.042 

2.63 

.064 

3.74 

nh3 

.046 

1.98  .028 

1.79 

.019 

1.19 

.035 

2.04 

Error 


12 


-.01 


-.07 


-58- 


ths  different  temperatures;  Figures  9 to  10  the  percentage  of 
nitrogen  in  tar  and  ammonia  at  each  temperature  and  Figures  11 
to  13  the  percentage  distribution  of  nitrogen  in  coke,  tar  and 
ammoni  a at  the  respective  temperatures. 

A comparative  study  of  these  graphs  is  very  useful  and 
brings  to  light  some  very  interesting  facts  regarding  the  consti- 
tution of  coal.  Thus  in  Figure  6 showing  the  quantities  of  tar 
given  off,  there  is  a decomposition  of  the  coal  at  450°  (or 
slightly  above)  yielding  a rapid  evolution  of  tar.  At  500°  C 
most  of  the  tar  has  been  given  off  in  all  cases  except  that  of 
No.  11,  which  continues  gradually  up  to  550°  C before  a lag  in 
the  curve  is  observed.  On  the  other  hand  in  the  case  of  ammonia 
(Fig.  7)  the  rapid  evolution  of  ammonia  only  begins  at  500°  C, 
This  again  is  true  in  all  cases,  except  that  of  No.  11,  when  the 
rapid  evolution  only  begins  at  550°  C.  'S’hus  in  all  cases  it  is 
shown  conclusively  that  the  molecule  containing  the  bulk  of  the 
nitrogen  only  starts  decomposing  after  all  the  tar  has  been  re- 
moved. Furthermore  this  decomposition  follows  directly  after  the 
expulsion  of  the  tar.  A small  portion  of  the  nitrogen,  however, 
comes  off  with  the  tar  and  is  closely  associated  with  it. 

Furthermore  it  is  seen  that  at  600°  C these  coals  yield 
quantities  of  nitrogen  as  ammonia  in  direct  proportion  to  the 
total  quantity  of  original  nitrogen  in  the  coal.  Thus  in  Figure 
10  coal  No.  3,  containing  the  highest  percentage  of  nitrogen 
liberates  also  the  greatest  amount  of  nitrogen  as  ammonia  at 
600°  C.  Coals  No.  14,  No.  7 and  No.  11  follow  in  order.  This, 
however,  is  not  the  case  at  lower  temperatures.  At  500°  coal 

No.  11  liberates  a greater  amount  of  nitrogen  than  coal  No.  7 


. 


■*'  - 

. 

. 

. 

■ 

• 

and  coal  No.  7 more  than  coal  No.  14.  This  is  further  evidence 
that  this  part  of  the  nitrogen  is  distinct  from  the  main  portion 
of  the  nitrogen  molecule.  The  behaviour  of  the  nitrogen  in  the 
tar  shows  the  same  character  (Fig.  9).  Here  again  we  find  that 
even  at  600°  C coals  Nos.  11  and  3 and  coals  Nos.  7 and  14 
approach  one  another  very  closely  in  their  percentages  of 
nitrogen.  In  all  cases  the  percentages  of  nitrogen  in  the  tar 
approach  a certain  limit  which  does  not  differ  to  any  extent 
with  different  coals. 

Considering  these  results  as  a whole,  though  limited 
in  scope  and  kind,  we  are  led  to  believe  that  the  nitrogen  in 
coal  exists  in  at  least  two  forms— the  one  a less  stable,  and 
the  other,  which  is  by  far  the  greater  part,  a very  stable  form. 
The  less  stable  form  comes  over  with  the  tar  and  is  closely  re- 
lated to  it.  There  is  no  evidence  to  show  that  the  tar  and  the 
nitrogen  belong  to  distinct  molecules.  On  the  contrary  the 
general  behaviour  of  the  coals  as  shown'  by  these  graphs  give 
strong  indications  that  tne  tar  and  the  nitrogen  originate  from 
different  parts  of  the  same  molecule.  ^ 

Figures  11,  12,  13  show  the  percentage  distribution  of 
the  nitrogen  in  the  coke,  tar  and  ammonia  at  different  tempera- 
tures. These  graphs  throw  some  light  on  another  property  of  the 
coal,  namely  its  stability  towards  heat.  Thus  coal  No.  14 
distributes  the  greatest  percentage  of  its  nitrogen  as  ammonia 
and  as  tar  at  600°  C (Fig.  13).  Coal  No.  14,  therefore,  de- 
composes most  rapidly  after  the  temperature  of  decomposition  is 
reached.  Coal  No.  3 on  the  other  hand  decomposes  rapidly  up  to 


-40- 

550°  but  stops  decomposing,  as  far  as  nitrogen  is  concerned,  at 
this  temperature,  indicating  greater  stability  of  the  nitrogen 
molecule.  The  decrease  of  the  nitrogen  distribution  in  the 
coke  (Fig.  11)  illustrates  the  point  in  question  in  a still  more 
interesting  way.  In  all  cases  except  No.  3 the  decrease  is 
continuous.  In  the  case  of  No.  3 the  decomposition  stops  at 
550°  C.  This  temperature  of  greater  stability  is  important  and 
seems  to  be  distinct  for  each  coal.  Probably  at  this  tempera- 
ture we  get  a decomposition  of  another  kind  leaving  the  nitrogen 
in  a form  which  is  not  easily  decomposed  by  heat.  It  is  also 
possible,  however,  that  the  more  stable  form  of  nitrogen  men- 
tioned above,  itself  exists  in  two  forms — the  one  more  stable 
than  the  other. 

It  is  further  possible,  and  very  likely,  that  we  have 
here  a case  of  polymerisation.  The  changes  which  take  place 
follow  one  another  in  direct  succession,  which  suggests  such  a 
state  of  affairs  very  strongly.  Frans  Fischer  (4S)  believes 
that  the  humic  acid  present  in  the  coal  polymerises  during  the 
course  of  its  formation  to  form  humin.  It  is  not  unlikely  that 
this  same  condition  exists  in  the  resinous  part  of  the  coal  and 
that  the  intricate  nature  of  all  coals  is  due  almost  entirely 
to  the  degree  of  polymerisation  of  the  compounds  present. 

Figure  8 shows  the  yield  of  gas  given  off  at  different 
temperatures.  There  are  no  sudden  breaks  in  these  curves.  In 

fact  the  increase  in  gas  is  more  or  less  gradual  and  consistent 
between  these  temperatures.  It  appears  that  the  gas  originates 

from  a different  part  of  the  coal  altogether,  and  for  the  sake 
of  convenience  we  might  look  upon  coal  as  being  made  up  of  two 


■ 


. 

. 


. 


. 


. 

- 


. 


. 

. 


. 


“-43" 


Fig.  7 SHOWING  QUANTITIES  of  AMMO NI A GIVEN  OFF  BETWEEN  4S0°C-680oC 


44- 


Fig. 


SHOWING  QUANTITIES  OF  GAS  GIVEN  OFF  BETWEEN  J$60°- 660 °C 


* 

-46- 

SHQWING  PERCENTAGE  NITROGEN  GIVEN  OFF  AS  AMMONIA 
BETWEEN  460 °- 600 °C 


-48- 

Fig*.  13  SHOWING  PERCENTAGE  DISTRIBUTION  OF  NITROGEN  IN  TAR 

BETWEEN  4S0°-660°C 


-4  ?<*- 

Fig.  13  SHOWING  PERCENTAGE  DISTRIBUTION  OF  NITROGEN 
GIVEN  OFF  AS  AMMONIA  BETWEEN  4Q'0°- GOO °C 


-48V- 


porticns,  (l)  the  gas  producing  and  (2)  the  tar  producing  portion 
By  the  gas  producing  portion  is  meant  that  portion  of  the  coal 
which  supplies  the  more  useful  gases  such  as  hydrogen  on  the 
action  of  heat  and  is  therefore  equivalent  to  what  is  often  call- 
ed the  "cellulosic"  portion.  The  "tar  producing'  portion" is  that 
part  of  the  coal  which  has  resulted  from  the  final  combination  of 
those  substances  originating  from  the  resins  and  proteins  in  the 
plant.  This  line  of  division  is  not  intended  to  be  absolutely 
marked,  but  rather  one  of  degree.  It  is  evident  that  the  hydro- 
carbons in  gas  originate  from  the  tar  producing  portion  of  the 
coal.  But  in  the  main  this  part  of  the  coal  is  not  gas  produc- 
ing. The  division  is  more  exact  than  those  previously  suggested 
and  is  in  agreement  with  the  theory  held  by  Taylor,  Porter, 
Thiessen,  Parr  and  others,  that  the  cellulosic  portion  of  coal 
is  the  first  to  decompose  on  heating,  rather  than  that  held  by 
Wheeler  and  his  co-workers,  that  the  cellulosic  or  "hydrogen 
producing"  part  of  the  coal  is  the  more  stable  to  heat. 

The  Effect  of  Steam  on  Coke  Residues 

Following  these  results  the  effect  of  steam  at  650°C 
and  750°C  was  tried  on  the  coke  residues  obtained  at  500°C  and 
600 °C.  The  apparatus  used  is  shown  in  Figure  14. 

2 gms  of  coke  were  placed  in  the  U tube  D,  made  of 
pyrex  glass.  In  each  side  of  the  tube  is  placed  a plug  of 
asbestos  wobl  and  finally  small  fireclay  blocks  about  the  size  of 
a pea.  Steam  is  generated  in  A,  and  at  the  same  time  tne  temper— 


--49“ 


-ature  of  the  furnace  is  raised  until  850 °C  is  reached.  The 
gases  are  then  passed  through  a condenser  and  into  E containing 

standard  ^ sulphuric  acid. 

10 

This  process  is  continued  for  two  and  a half 
hours  when  the  acid  in  E is  renewed  and  the  temperature  raised 
to  ?50°C.  The  contents  of  E obtained  at  650°C  are  now  distilled 
and  the  amount  of  ammonia  which  was  evolved  calculated.  At  ?50°6 
the  reaction  is  carried  on  for  3 l/2»4  hours  until  no  more 
ammonia  is  evolved  and  the  contents  distilled  as  before.  In 
this  way  an  estimation  is  obtained  of  the  exact  amount  of 
ammonia  given  off  at  these  two  temperatures  in  the  presence  of 
steam.  By  weighing  the  residue  and  analysing  it  for  nitrogen 
we  are  able  to  calculate  the  distribution  of  nitrogen  under 
these  conditions.  Tables  16,1?  show  the  effect  of  steam  on  the 
coke  residues  at  650 °C  and  750 °C  and  tables  18,19  the  percentage 
distribution  of  nitrogen.  The  nitrogen  which  is  listed  as 
" unaccounted  for  nitrogen",  in  the  tables  is  evidently  free 
nitrogen  arising  from  the  dissociation  of  ammonia  at  this  high 
temperature. 

The  percentage  of  the  nitrogen  liberated  from 
the  coke  is  in  all  cases  low.  At  these  temperatures  it  seems 
as  though  steam  has  little  effect  in  liberating  the  nitrogen 
In  order  to  do  this  a higher  temperature  is  evidently  necessary 
so  that  the  coke  and  steam  may  combine  to  form  a oxides  of 
carbon,  thereby  leaving  the  nitrogen  free  to  combine  with  the 
hydrogen  to  form  the  ammonia. 


■ 


. 


. 


. 


- 


' 


V 1 : I :7 


rig.  i4  — ftyparcijius  , showing  passage  oj  steam  over  coke 


-52- 


Table  13 

DISTRIBUTION  WITH  5a) °C  COKE 


Nitrogen 

3 E 

7 F 

11  G 

14  H 

as  Ammonia 

14.18 

18.52 

18.67 

16.57 

remaining 

behind  in 
coke  resi- 
due 

Unaccounted 

69.38 

69.34 

69.56 

72.12 

for  16.44  12.14  11.77  11.31 


Table  19 


DISTRIBUTION  WITH  600 °C  COKE 


Nitrogen 

3 M 

7 N 

11  0 

14  P 

as  Ammonia 

12.26 

14.82 

14.88 

13.59 

remaining  in 
coke  residue 

70.01 

69.34 

70.01 

71.61 

Unaccounted 

for 

17.73 

15.84 

15.11 

14.80 

-53- 

B,  Chemical  Reagents 

In  the  series  of  experiments  just  described  it  is 
evident  that  the  nitrogen  molecule  constitutes  the  tar  producing 
portion  of  the  coal,  and  that  the  structure  of  this  molecule,  in 
one  respect,  constitutes  the  structure  of  coal.  In  the  experiments 
which  are  to  follow  attempts  are  made  to  isolate  the  nitrogen  mole- 
oule  or  break  it  up  by  the  action  of  chemical  reagents  in  such  a 
way  that  it  may  be  recognised  in  its  original  form  in  the  coal. 

According  to  the  theoretical  considerations  described 
above  it  is  evident  that,  after  hydrolysis  of  protein  has  taken 
place , several  reactions  may  again  take  place  amongst  the  products 
of  decomposition.  All  of  these  products  being  acids,  they  may  act 
as  such  on  other  organic  compounds  in  the  plant  to  form  open  chain 
derivatives,  or  ring  compounds  of  a more  stable  nature.  On  the 
other  hand  they  may  remain  in  the  coal  as  such  in  a highly  poly- 

r 

meised  form  or  they  may  decompose  altogether  and  pass  off  in  the 
form  of  Ng  and  ammonia  in  the  secondary  stages  of  coal  formation. 

In  order  to  get  some  idea  of  any  such  secondary  changes 
which  may  have  taken  place, certain  chemical  reactions  were  tried 
on  the  coal,  keeping  the  temperature  in  all  cases  as  low'  as  pos- 
sible . 

In  the  first  series  of  reactions  the  effect  of 
hydrolysing  agents  was  tried  on  the  coal. 

Hydrolysing  Agents 

In  all  these  reactions  preference  was  given  to  the 
method  of  examining  the  residue  for  nitrogen  rather  than  the  ex- 


. 





• . 


-54- 


tract,  $n  each  case  the  percentage  of  nitrogen  in  the  residue  was 
determined  and  calculated  to  the  ash  and  moisture  free  basis. 

Thus  by  comparing  this  figure  with  the  original  percentage  of 
nitrogen  in  the  coal,  calculated  on  the  moisture  and  ash  free  basis 
a satisfactory  indication  of  the  extent  to  which  the  nitrogen 
molecule  was  affected  can  be  obtained.  The  following  hydrolysing 
agents  were  tried. 

a.  Two  different  strengths  of  hydrochloric  acid  were  used, 
namely  a 12 6jo  and  a 40  fc  solution.  50  gms  of  coal  v/ere  heated  under 
a reflux  condenser  for  10  hours  with  an  excess  of  these  solutions. 
The  residue  was  washed  until  the  wash  water  is  free  from  acid  and 
the  air  dried  and  analysed, 

b.  N.  Zelinsky  (54),  preferred  using  fomic  acid  for  hydroly- 
sing purposes,  so  that  in  these  experiments  a 25  fc  solution  of 
fomic  acid  was  tried  as  well. 

c.  Aquous  Potassium  Hydroxide  v/as  tried  in  three  different 

strengths  1,  5 ;2,10  3,50  The  residues  were  washed  to  • 

give  no  coloration  with  phenolphthaleine , air  dried  and  analysed. 
The  extracts  were  coloured  brownish  red,  the  intensity  of  the 
colour  increasing  with  the  strength  of  the  solution  of  potassium 
hydroxide  used.  The  extract,  on  treatment  with  HC1  gave  a white 
gelatinous  precipitate  soluble  in  excess.  The  same  precipitate 
was  produced  with  all  other  common  acids.  In  excess  quantities  of 
alcohol  the  precipitate  was  insoluble  and  was  separated  in  this 
way  from  the  extract.  It  was  found  to  be  aluminum  oxide.  The 
solution  was  finally  evaporated  to  a small  bulk  and  tested  for 
nitrogen  with  negative  results. 

a.  A 10  fc  alcoholic  potash  solution  was  used  in  a similar  way 


« 


•X 


. 

. 

. 


-55- 


(1)  at  the  ordinary  pressure  and  (2)  at  3 atmospheres  pressure. 

Table  20  shows  the  results  obtained  in  these  reactions 
In  all  these  cases  a certain  amount  of  resinous  bodies  are  ex- 
tracted from  the  coal,  together  with  quantities  of  alumina  and  iron 
The  table  clearly  indicates  that  the  main  part  of  the  nitrogen 
molecule  remains  unaffected.  It  is  also  evident  that  a very  small 
portion  of  the  nitrogen  has  been  removed. 

If  the  reagent  attacks  only  the  ash  of  the  coal,  then 
the  ash  content  would  be  lowered  and  the  nitrogen  content  corres- 
pondingly raised,  and  the  percentage  of  nitrogen  on  the  moisture 
and  ash  free  basis  would  not  be  altered.  But  if  the  volatile  matter 
in  addition  is  attacked  so  as  to  remove  some  of  it,  then  the  ash 
and  nitrogen  content  would  be  raised  and  the  percentage  of  nitrogen 
calculated  on  the  moisture  and  asn  free  basis  would  be  higher.  In 
all  cases  a certain  amount  of  the  volatile  matter  is  removed.  It 
is, therefore,  seen  that  all  of  the  above  reactions  have  had  a 
small  effect  on  the  nitrogen  content  ofthe  coal. 

An  attempt  was  then  made  to  determine  quantitatively 
the  amount  of  nitrogen  that  was  removed  in  the  above  reactions. 

This  nitrogen  we  would  expect  to  be  in  the  form  of  acid  amides 
and  amino  acids,  and  in  order  to  determine  their  amounts  quantit- 
atively the  following  methods  were  employed. 

i 

20  gms  of  coal  are  placed  in  a one  litre  round  bottom 
flask  and  heated  under  reflux  for  3-4  hours  with  300CC  of  hydro- 
chloric acid  (1.1).  The  mass  is  then  filtered  under  suction  and 
the  residue  washed  with  hot  water.  The  solution  is  evaporated 
down  to  a small  bulk,  transferred  to  a measuring  flask  and  made  up 
to  100  CC.50C0  of  this  amount  was  k jfcldalilized  to  give  the  total 


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-57- 

amount  of  amido  and  amino  nitrogen  present.  The  remaining  50  C C 
of  this  amount  were  used  to  determine  the  amido  nitrogen,  by  dis- 
tilling a known  quantity  in  the  presence  of  cream  of  magnesia. 

The  amido  nitrogen  alone  distills  over  as  ammonia  which  is  col- 
lected in  standard  acid.  The  difference  in  the  two  results  gives 
the  amount  of  amino  nitrogen  present. 

All  fourteen  samples  of  coal  weretr eated  in  his  way  and 
the  results  tabulated  (table  21) . It  is  seen  that  the  amount  of 
amido  nitrogen  is  in  almost  all  cases  greater  than  the  amount  of 
amino  nitrogen.  This  is  what  we  would  expect,  if  results  obtained 
by  Kelley  (55)  on  the  rate  of  ammonif ication  of  these  forms  of 
nitrogen  can  be  applied  in  this  case.  Kelley  added  protein  sub- 
stances to  quartz  sand,  previously  treated  with  soil  infusion 
and  studied  the  rate  of  ammonif i cat i on.  He  f ound, contrary  to  ex- 
pect at  ion,  that  the  basic  nitrogen  fraction  was  more  completely 
ammonified  than  either  the  amido  or  non-basic  fraction.  Lathrop 
a little  later  (56)  came  to  similar  conclusions. 

The  amounts  of  amido  and  amino  nitrogen  present  in  the 
coal  are  surprisingly  low  and  in  craer  to  be  able  to  come  to 
definite  conclusions  regarding  this  matter,  an  attempt  v^as  made 
to  remove  all  KHg  groupings  in  another  way. 

When  carbonyl  chloride  is  passed  over  heated  amines 

a carbamie  chloride  is  formed,  y;hich  readily  loses  HC1  to  form 
an  isocyanate. 

RfiiV  cecoce  — » R.rsHCoft  — > R.n-c-o  *2 Hci. 


. 


. 

. 

» 


-58- 

Table  31 

SHOWING  PERCENTAGE  OF  NITROGEN  PRESENT  AS  AMIDES 
AND  AMINO  ACIDS 


Coal 

Nitro  gen 
as 

Nitrogen  as 

Total  "NH2" 

fo  of 

Amides 

Amino  Acids 

Nitrogen 

Total 

1 

.0078 

.0048 

.0122 

.57 

2 

.010 

.0076 

.0176 

<-• 

co 

o 

3 

.0336 

.0026 

.0362 

1.56 

4 

.020 

.0094 

.0294 

1.35 

5 

.0125 

.0127 

.0252 

1,50 

6 

.0124 

.0125 

.0249 

1.54 

7 

.0112 

.0042 

.0154 

.92 

8 

.0155 

.0069 

.0224 

1.46 

9 

.0140 

.0082 

.0222 

1.33 

10 

.0309 

.0030 

.0339 

1.60 

11 

.0175 

.014 

.0184 

1.14 

12 

.020 

.0045 

.0265 

1.53 

13 

.0186 

.0071 

.0257 

1.47 

14 

.010 

.007 

.0170 

.95 

-59- 

The  isocyanic  esters  axe  volatile  liquids  with  a powerful  un- 
pleasant smell. 

If  coal  contains  amino  groupings  then,  when  C0C1  is 

2 

passed  over  it  at  higher  temperatures,  we  should  expect  the  corr- 
esponding nitrogen  compounds  to  volatilize. 

100  gms  of  previously  dried  coal  were  placed  in  a long 
tube  furnace,  which  was  electrically  heated.  The  temperature  was 
controlled  by  means  of  a thermometer  placed  at  each  end.  The 
C0Clo  was  purified  by  passing  it  through  cotton  seed  oil  and 
finally  over  the  coal  at  250°C  and  350°C.  The  results  given  in 
the  case  of  two  coals  show  conclusively  that  very  little  action 
took  place.  (Table  22) 

Table  22  SHOW IMG  EFFECT  OF  CARBONYL  CHLORIDE 

Treatment  Expt.  No.  H^o  Ash  Ohg.  % 

— - free  basis  h„0  & Ash 

Ng  * free 


250° 

14* 

1.36 

11. 

,37 

190 

2.18 

2.05 

350° 

14 

1.36 

11. 

,83 

1.89 

2.19 

2.05 

350° 

2 

3,. 

1.45 

7, 

,11 

2 • 35 

2.57 

2.55 

We  axe  now  in  a better  position  to  formulate  our  theorjf 
as  to  the  changes  which  the  protein  molecule  undergo  during  the 
different  stages  of  coal  formation.  The  monamino  , diamino  acids 
and  acid  amides  which  come  into  the  mass  as  decomposition  products 
of  the  protein  molecule,  are  no  longer  present  to  any  extent  in 
the  coal.  Consequently  these  compounds, eitner  combined  with 
themselves  or  with  other  organic  compounds  to  form  more  stable 
ring  derivative s , or  they  are  decomposed  and  pass  off  from  the 


-60- 


mass  in  the  form  of  ammonia  or  nitrogen  , thus  leaving  the  heter 
ocyclic  compounds, which  are  present  in  proteins,  to  form  the 
bulk  of  the  nitrogen  found  in  coal.  It  is  an  established  fact 
that  amino  acids  and  acid  amides  will  readily  ammonify  in  the 
presence  of  bacteria  in  the  soil.  We  axe, therefore,  more  entitled: 
to  assume  such  a state  of  affairs  in  the  case  of  coal  than  we  are 
to  assume  sjtiGifcx  a state  of  further  combination.  The  conditions 
during  coal  formation  are  favorable  for  such  decompositions.  The 
fact  that  all  coals  from  the  same  locality  contain  amounts  of 
nitrogen  which  are  more  or  less  constant,  further  suggests  a com- 
pound which  is  stable  to  the  natural  agencies  to  which  it  is  ex- 
posed . The  heterocyclic  compounds  are  the  only  portions  of  the 
protein  molecules  that  will  satisfy  this  condition.  If  this  is 
the  case  then  in  order  to  account  for  some  of  the  properties 
of  coal,  we  rust  assume  that  these  compounds  have  undergone 
polymerization  to  a great  and  unknown  extent. 

i w 

Selenium  Oxychloride 

According  to  researches  done  by  Prof.  Lenher  of  the 
University  of  Wisconsin,  Selenium  oxychloride  is  a very  useful 
and  active  selective  solvent.  Its  effect  was  therefore, tried  on 
coal  as  an  attempt  to  separate  the  stable  nitrogen  molecule. 

Five  grammes  of  coal  No. 3 and  25  CC  of  pure  selenium 
oxychloride  were  placed  in  a conical  flask  and  corked.  The 
mixture  is  warmed  and  shaken  continually  for  1/4  hour,  when  the 
extraction  is  assumed  to  be  complete.  In  order  to  get  this 
solution  to  filter  so  as  to  separate  the  residue  from  the  extract 


. 


■ 


* 


. 


. 


-61- 


the  mixture  is  diluted  with  200  C C of  benzene.  Filtering  under 
suction  is  thus  rendered  possible.  The  residue  is  now  washed 
well  with  benzene  to  remove  as  far  as  possible  any  adhering 

SeOCl  then  with  ether  and  finally  dried  at  105°C. 

2 

The  extract  when  heated  with  water  deposits  red 
selenium.  When  benzene  alone  is  mixed  with  selenium  oxychloride 
in  these  proportions  and  water  added  to  the  mixture,  the  selen- 
ium oxychloride  hydrolyses  to  selenic  and  hydrochloric  acids  with 
-out  any  deposit  of  the  element.  Thus  when  selenium  oxychloride 
acts  on  coal  a chemical  reaction  is  assumed  to  take  place  and  a 
compound  is  formed  which  readily  deposits  selenium. 

The  extract  was  treated  with  excess  of  sodium 
hydroxide  and  steam  distilled.  Finally  it  was  vacuum  distilled 
but  no  nitrogen  compounds  were  found. 

The  residue  was  analysed  for  nitrogen  and  results 
calculated  to  the  moisture  and  ash  free  basis.  Finally  for 
purposes  of  comparison  the  action  of  selenium  oxychloride  was 
tried  on  500°C  coke  obtained  in  previous  experiments  (see  table 
9) . This  coke  had  practically  all  its  tar  already  removed  . 

The  reaction  was  significant.  Hardly  any  result  could  be  seen, 
except  a coloration  of  the  solution,  showing  that  the  selenium 
oxychloride  reacted  with  the  tar  in  the  coal.  The  mass  was 
easily  filtered  and  the  residue  washed  with  benzene  and  ether 
and  finally  analysed.  The  results  are  given  in  table  23. 


Table  2b  SHOWING  ACTION  OF  SELENIUM  OXYCHLORIDE 
Treatment  Expt.  H*Q 


Ash 


N; 


Orig.  Ns 


Coal  & SeOCL: 


32 


HaQ.Ash  free  HaQ.  Ash  fr 
6.23  1. 79  2.55 


be 


-62- 

Table  33  SHOWING  ACT 

Treatment  Exot . h2Q 

Coal  & SeOCla  3' 

(residue) 

Coke  & SeOCl2  3”  2.07 

(residue) 

orignial  coke  3,,f  .54 

550 °C ( 3E) 

From  these  figures  it  appears  that  the  nitrogen 

in  the  coke  remains  unaffected.  In  the  case  of  the  coal  it  would 

appear  as  though  some  of  the  nitrogen  was  removed.  Selenium 

oxychloride  on  the  other  hand  is  extremely  active  dnd  forms  a 

compound  with  the  coal,  so  that  it  is  impossible  to  rid  the  residue 

of  the  reagent.  This  is  seen  very  forcibly  by  the  result  obtained 

in  a volatile  matter  determination  on  the  residue.  It  was  found 

matter 

that  the  volatile/on  treatment  with  SeOCl2  increased  in  the  case 
of  coal  NO§  from  33.10  to  31.34  $>.  Taking  these  figures  into 
account  the  two  results  coincide  showing*  conclusively  that 
selenium  oxychloride  will  not  attack  the  stable  part  of  the  nitroge:] 
molecule . 

The  Action  of  Reducing  Agent 3 

Subsequent  to  these  results  the  coal  was  subjected 

to  the  action  of  reducing  agents  in  order  to  observe  what  effect 

hydrogenation  would  have  on  the  nitrogen  molecule. 

When  pyrrol  is  reduced  pyrroline  is  obtained.  With 
strong  reducing  agents,  such  as  red  phosphorus  and  hydr iodic  acid 

pyroline  is  further  reduced  to  alkylarnine  or  still  further  to 


ON  OF  SELENIUM  OXYCHLOrtlDE 


Ash 

6.23 

N a 

1.79 

HpO.Ash  free 

1.91 

Orig.  N 
h20,  A 

S.55 

7 .94 

2.65 

2.94 

2.96 

9.14 

2.68 

3.96 

2.96 

lh 
fred 


* 


. 


1 

■ 


■ 


hydrocarbon  and  ammonia  as  is  illustrated  by  the  following  form- 
ulas: 


& 

— > 


CH3(CHz)3NHz  — » CHi(CHu)%CH3  + flH3. 


If  the  nitrogen  in  coal  is  present  in  the  form  of 
pyrrol  derivatives,  as  we  have  been  led  to  believe,  then  strong 
reducing  agents  should  have  some  effect  on  the  nitrogen  molecule. 
In  order  to  try  out  this  reaction  propyl  alcohol  and  sodium, 
and  red  phosphorus  and  hydriodic  acid  were  used  as  reducing  agents 
(a)  Proovl  Alcohol  and  Sodium 

20  gms  of  coal  were  placed  in  a two  litre  round 
bottom  flash  containing  a reflux  condenser  and  500  gms  of  propyl 
alcohol  added.  The  mixture  is  warmed  to  boiling  and  small  pieces 
of  sodium  added.  The  flask  is  shaken  continually  so  that  the 
contents  are  kept  mixed  all  the  time.  When  no  more  sodium  reacts 
sufficient  water  is  added  to  decompose  any  free  sodium,  At  this 
stage  the  coal  assumes  the  appearance  of  a soft,  oily  resinous 
mass,  which  floats  on  the  surface  of  the  liquid.  The  mixture  is 
cooled,  filtered  washed  and  air  dried.  But  while  being  air  dried 
the  coal  seems  to  undergo  oxidation  again  and  is  converted  back 
into  its  original  appearance.  Table  24  shows  its  analysis  on 
the  moisture  and  ash  free  basis.  Evidently  very  little  nitrogen 
was  removed  in  this  case. 

(b)  Hvdrlodio  acid  and  Red  phosphorus 

The  reaction  with  hydriodic  acid  and  red  phosphorus 
at  higher  temperatures  is  more  difficult  to  carry  out  successfully 
owing  to  the  enormous  pressure  set  up  during  the  reaction.  A 
mercury  container  with  a specially  designed  screw  cap  was  used. 


-64- 


At  200°C  the  reaction  was  carried  out  successfully  but  at  higher 
temperatures  the  container  failed  to  withstand  the  pressure 
entirely  and  leaked  through  the  cap.  For  this  reason  experiment 
( 14C)  could  not  be  run  satisfactorily,  though  a certain  measure 
of  success  is  evident  from  the  amount  of  nitrogen  that  was  re- 
moved in  the  process. 

50  gms  of  coal  were  mixed  with  10  gms  of  red 
phosphorus  and  350  gms  of  hydrogen  iodide  of  50  strength. 

The  mixture  was  heated  for  two  hours  (a)  between  180-200°C 
and  (b)  250°-280°C.  On  cooling  and  filtering  the  residue  and 
extract  in  the  latter  case  were  treated  as  follows: 

( 1)  Treatment  of  residue; 

The  residue  was  treated  with  iodine  and  water 
and  boiled  for  a short  time  to  remove  any  excess  phosphorus. 

The  phosphorus  and  iodine  combine  to  form  PIa  which  is  decomp- 
osed by  water,  forming  phosphoric  acid  which  is  soluble  and 
hydrogen  iodide  which  passes  off  as  a gas.  The  excess  of  iodine 
is  removed  by  'washing  with  a strong  solution  of  potassium,. 

Iodide  and  finally  with  7/ater  to  remove  the  latter.  Finally  it 
is  air  dried  and  an aly sed, (Table  24) 

( 2 ) Treatment  of  the  Extract 

The  extract  was  a green  color.  On  diluting  it 
with  water  a brilliant  yellow  precipitate  settles  out.  This 
precipitate  contained  carbon,  hydrogen,  oxygen  and  iodine. 

On  boiling  with  water  it  hydrolyses  to  a white  insoluble  sub- 
stance containing  the  first  three  elements  mentioned  above. 

As  the  precipitate  contained  no  nitrogen  it  was  not  investigated 


-65- 

any  further. 

On  removing  this  precipitate,  however,  the  solution 
v/ as  steam  distilled  in  the  presence  of  sodium  hydroxide.  The 
steam  distillate  had  a distinct  ammoniacal  smell  and  aave  a dense 
precipitate  with  Nessler' s reagent.  No  amimes  could  be  detected 
•with  benzene  sulphonyl  chloride.  Table  24  (exp.  14C)  shows 
that  quite  a large  proportion  of  the  nitrogen  was  removed  in  this 
process. 


Table  24  SHOWING  EFFECT  OF  REDUCING  AGENTS 


Treatment 

Expt . 

Ha0 

Ash 

n2 

Naf ree 

Orig  Nafree 

H20  & Ash 
basis 

HaO  & Ash 
basis 

Na 

& 

c3h?oh 

14  A 

3.  29 

10.52 

1.69 

1 . 98 

2.05 

HI  & Phos. 
180-200 

14  B 

1.44 

14.10 

1.67 

1.98 

2,05 

HI  & phos. 
250-280 

14  C 

1.16 

30.26 

1,04 

1.52 

2.05 

In  these  results  we  have  further  indiaations  of  the 
presence  of  pyrrol  derivitives  in  coal.  The  fact  that  such  a 
high  temperature  and  pressure  is  necessary  in  the  reaction  further 
suggests  polymensati on  of  these  compounds. 


. 


. 


» 


-66-' 

SUMMARY  OH  THE  ROEk  Off  iUTROGM  IH  OPAL 

The  experimental  data  arrived  at  in  this  work 
indicates  certain  theories  regarding  the  constitution  of  coal 
and  the  form  in  which  the  nitrogen  exists.  All  past  theories 
on  coal  take  into  account  cellulosic  and  resinic  decomposition 
products  and  state  that  coal  is  made  up  of  these  two  portions 
alone.  This  work  shows  conclusively  that  the  nitrogen,  or 
the  decomposition  products  of  protein  cannot  be  neglected. 

The  nitrogen  molecule  is  closely  related  to  the  resinic  port- 
ion of  coal , and  forms  different  parts  of  tne  same  molecule 
from  which  the  tar  originates. 

Two  main  forms  of  nitrogen  have  been  established 
in  this  work;  l:  RH2  form,  present  as  amino  acids  and  acid 

amides,  and;  £:  a more  stable  form,  probably  in  the  form  of 

a pyrrol  ring  which  has  undergone  polymerisation.  The  BH2 
form  does  not  constitute  more  than  1*6%  of  the  nitrogen  in 
the  coals  studied.  As  amino  acids  and  acid  amides  readily 
undergo  ammonificati on  in  the  presence  of  bacteria,  it  is 
quite  probable  that  they  decompose  and  pass  off  from  the  coal 
mass  during  the  period  of  formation.  The  heterocyclic  com- 
pounds, which  are  present  in  proteins  in  the  form  of  pyrrol 
rings,  on  the  other  hand,  remain  behind  and  account  for  the 
more  or  less  constant  percentage  of  nitrogen  in  all  coals 
from  tne  same  locality.  The  pyrrol  derivations  undergo  poly- 
merisation to  an  unknown  degree  in  the  presence  of  the  organic 
acids  in  the  vegetal  matter,  and  combine  with  the  products  of 


■ 


-67- 


decomposition  arising  from  the  resinic  matter  in  plants. 

These  products  of  decomposition  are  thus  present  in  the  form 
of  long  side  chains  attached  to  the  polymerised  pyrrol  ring. 

The  author  would  suggest  that  this  compound  be  called  the 
"tar  producing  portion"  of  the  coal. 

When  coal  is  heated  tnese  side  chains  split  off  and 
distil  over  in  the  form  of  tar.  The  HUE  nitrogen  comes  off 
with  the  tar  and  quite  probably  is  present  in  these  side 
chains.  This  accounts  for  the  small  percentage  of  ammonia 
given  off  at  low  temperatures.  When  practically  all  of  the 
tar  has  been  split  off,  the  polymerised  pyrrol  derivative  starts 

decomposing  in  stages  and  liberates  ammonia  and  hydrocarbons. 

relatively 

This  accounts  for  the/ small  percentage  of  hydrocarbons  found 
in  gas.  In  this  case  acetylene  will  evidently  be  formed.  Part 
of  this  acetylene  combines  with  hydrogen  to  form  ethylene  and 
methane,  and  a further  portion  polymerises  to  form  benzene, 
if  the  conditions  are  favorable.  Finally  a stage  is  reached 
where  the  polymerised  compound  is  unsaturated  and  at  the  same 
time  unstaole.  At  this  temperature  the  ring  breaks  and  a com- 
pound remains  in  which  nitrogen  is  probably  combined  directly 
with  carbon.  When  this  stage  has  been  reached  the  foeiat  way  to 
obtain  the  nitrogen  in  the  form  of  ammonia,  is  oy  burning  a- 
way  the  carbon  in  the  presence  of  steam. 

On  these  lines  the  presence  of  pyrrol  and  pyridine 
in  coal  tar  can  be  explained,  since  it  is  a distinct  property 
of  five  membered  heterocyclic  compounds  containing  nitrogen  to 
be  converted  into  six  membered  ring  compounds.  Pyrrol  derivht- 


■ 


-68- 


“ 

ives  furthermore  readily  polymerise  in  the  presence  of  acids 
and  these  polymerised  products  decompose  on  heating  to  yield 
ammonia.  The  fact  that  polymerised  pyrrol  derivatives  are  un- 
stable at  higher  temperatures  indicates  that  the  degree  and  kind 
of  polymerisation  which  takes  place  during  the  stages  of  coal 
formation  is  yet  unknown. 

In  regard  to  the  actual  behavior  of  the  nitrogen 
in  the  coals  studied,  the  following  conclusions  are  drawn :- 

1:-  In  distillation  experiments  carried  out  between 

450  degrees  and  600  degrees  0 the  percentage  of  the 
nitrogen  remaining  behind  in  the  coke  is  distinct  for 
each  coal  and  is  independent  of  the  total  amount  of 
nitrogen  in  the  coal.  As  much  as  98.85$  of  the  nitro- 
gen remains  in  the  coal  at  450  degrees  C in  one  case. 

In  this  instance  only  .05$  of  the  nitrogen  is  liber- 
ated as  ammonia.  At  600  degrees  G an  average  of  95$ 
of  the  nitrogen  remains  in  the  coal  and  not  more  than 
2.0 4%  of  the  nitrogen  is  liberated  as  ammonia.  On 
further  heating  to  750  degrees  G in  the  presence  of 
steam  an  average  of  70%  of  the  nitrogen  remains  in 
the  coke. 

2:-  Hydrolysing  agents  will  affect  the  M2  nitrogen  in 
the  coal,  but  not  the  more  stable  form. 

3:-  In  the  coals  studied  the  percentage  of  HH2-nitrogen 
varied  from  .57%  to  1.60$  of  the  total  nitrogen 
present.  In  almost  all  cases  the  greater  part  of  this 
nitrogen  was  in  the  amido  form. 


-69- 

4:-  Selenium  oxychloride  will  react  with  the  tar  in  coal 
and  form  a colloidal  mass  with  it.  It  does  not 
attack  the  stable  form  of  nitrogen. 

5:-  Strong  reducing  agents  will  attack  the  nitrogen  in 
coal  to  yield  ammonia.  Thus  red  phosphorus  and  Hydriodic 
acid  at  250  degrees  to  280  degrees  reduces  the  percentage 
of  nitrogen  from  2.05%  to  1.5%,  calculated  on  the  moisture 
and  ash  free  basis. 


-70- 

BIBLIOGRAPHY 


A.  On  the  nitrogen  content  of  coal  and  the  distribution  on 
di stillation. 

1.  Swindells  B.  P. , June  1844. 

2.  Berthelot,  M.  Comptes  Bendas  67--1141. 

3.  Henin,  J.  Gaslight  (1892)  p.  296. 

4.  Mayer,  M.  H.  F.  , Altmayer,  7.  The  formation  of 

ammonia  in  the  dry  distillation  of  coal.  J.S.C.I. 
26.  125-6.  (1907) 

5.  McLeod,  J.  Redistribution  of  nitrogen  in  the  distill- 

ation of  coals.  J.S.C.I.  26.  135-6.  (1907) 

6.  Short,  A.  Carbonization  of  Durham  Coking  coals  and 

the  distribution  of  nitrogen  and  sulphur. 

J.S.C.I.  23,  581-85. 

7.  Woltereck,  H.C.  Production  of  ammonia  and  the  re- 

covery of  nitrogen  in  heat.  Comp.  Rend.  152, 
1245-7  (1911) 

8.  Summer sbach,  0.  Formation  of  ammonia  and  cyanogen  in 

coal  distillation.  Stahl  und  Risen  34,  1153-9. 
(1914) . 

9.  Cobib®,  J."r.  A problem  of  modern  gas  practice. 

J.  Gas  Lighting  126,  329-3.  (1914) 

10.  Summersbach,  0 (a)  Yield  of  nitrogen  in  coal. 

Coll.  Guard  109,  1020  (1915) 

11.  ” (b)  Formation  of  ammonia  and  cyan- 

ogen during  carbonization. 

J.  Gas  Lighting  131,  246-7  (1915) 


. 


-71- 


12.  Terres,  E.  A study  of  the  formation  of  the  nitrogen 

in  coal  and  coke.  Chem.  Ztg.  39  — 73  (1915) 

J.  Gasbel  59  519  — 21. 

13.  Porter,  H.C.  Goal  and  coke  by  products  as  a source 

'for  fixed  nitrogen.  Chern.  Met.  Eng.  15,  470-5. 

(1916) 

14.  Mahler,  P.  Nitrogen  content  of  oxidised  coals. 

Comp.  Rend.  165  634  (1917) 

15.  Gluud,  W.  , & Brener,  P.K.  Distribution  of  the  nitrogen 

of  coal  on  low  temperature  carbonization. 

Ges  Abhandt  Zur  Remit) nis  der  Kohle  3.  227-37. 

(1920) . 

16.  Monkhouse  & Cobb,  J.W.  Liberation  of  nitrogen  from 

coal  and  coke  as  ammonia.  Gas  J.  156,  234-40. 

(1921 ) 

16a.  Chiles,  H.C.  The  form  of  nitrogen  in  coking  processes. 

University  of  Illinois.  Thesis (unpublished ) 1920. 

B.  On  the  Constitution  of  Coal. 

17.  Guignet , E.  Constitution  of  Coal.  Comp.  Rend.  88,  590.  j 

(1879) 

J.C.S.  36.  602.  (1879) 

16.  Friswell , R.J.  Notes  on  the  action  of  dilute  nitric  acic 
on  coal.  Proc.  Chem.  Soc.  (1892)  105-9. 

19.  Smith,  A contribution  to  our  knowledge  of  the  sol- 

uble and  resinic  constituents  of  bituminous  coal. 
J.S.C.I.  (1891)  10  975. 

20.  Smythe , The  proacinonate  constituents  of  coal. 

Interim  Report  of  Comm,  of  B.  Assoc.  (1894)  p246. 

21.  The  constituents  of  coal. 

Interim  Report  of  Comm,  of  B.  Assoc.  (1896)  p 340. 


' 


-72- 

22.  Anderson,  W.  C.  & Roberts,  J.  , Some  Chemical  properties 

of  Scotch  Coals.  J.S.C.I.  (1898)  17.  1013- 

23.  Baker,  T.  Solvent  action  of  Pyfidirle  on  coals. 

J.S.C.I.  (1901)  20  789. 

24.  Bona tn  B.  , & Margosches,  B.  An  addition  to  the  invest- 

igation of  coal.  Chem  Ind.  (1902)  226. 

25.  Bonath--Britnn  Eossil  Coals.  Zeit  £ Angew  Chem  19, 

657  ( 190o ) 

x iro 

26.  Bedson,  P.P.  Botes  on  the  proscejmate  constituents  of 

coal.  J.S.C.I.  27  147  (1908) 

27.  Boudouard,  0.  humic  substances  from  coal. 

Comp.  Rend.  147  486 

28.  Lewes,  V.B.  Progressive  age  29,  1030  (1911) 

29.  Pictet,  A.  & Ramseys  L.  Constituents  of  coal. 

Be.  44  2486-97  (1911) 

30.  Burgess,  M.  J.  Sc  Wheeler , R.V.  The  volatile  constituents 

of  coal.  J.S.C.OI.  30  606  (1911) 

31.  Eraser  & Hoffman  The  constituents  of  coal  soluble  in 

phenol.  Tech  paper  53.  of  Mines.  (1912) 

32.  Pictet,  A.,  h Ramseys  L.  Hydrocarbons  from  coal. 

Arch  Sci.  Phys.  Hat.  34,  234-49  (1913) 

33.  Clarke,  E.F.  , & Wheeler,  R.V.  Volatile  constituents 

of  coal.  J.C.S.  103  1904.  (1913) 

34.  Parr,  S.  W.  and  Hadley,  H.  E.  The  analysis  of  coal 

with  phenol  as  solvent.  B 76  U. of  I.  Exp.  Stn. 

34a.  Hager  Coal  and  the  Chemistry  of  its  carbonization. 

J.S.C.I.  (33)  389-392  (1914) 

35.  Jones  & Wheeler  The  constituents  of  coal. 


J.C.S.  109  707  (1916) 


. 


-73- 


36.  Porter,  H.G.  and  Taylor,  G.B.  The  primary  volatile 
products  of  the  carlo ni zat ion  of  coal. 

Tech.  Pap.  140  B.  of  M. 

57.  Stopes,  M.  & Wheeler , R.V.  The  structure  of  coal. 

J.  .G.I.  56.  176-8  (1917) 

56.  White,  D.  , Thiessen  & Davis.  The  origin  of  coal. 

B.  58.  B.  of  Mines  (1913) 

59.  Thiessen.  R..  Stricture  in  Paleozoic  Bituminous  Goals. 

B.  117  3.  of  M.  (1920) 

40.  Hilpert,  W.  S. , Keller,  E. , Lepsius,B.  Action  of 

Chemical  reagents  ©h  coal. 

Ge© . Ahhandt  Zur  Kennfciris  der  Kohle  (1917)  1 22-5. 

41.  Groppel,  H.  8s  Fischer,  F.  Extraction  of  previously 

heated  coal. 

Gee.  Ahhandt  Zur  Kenntnis  der  Konle  I 88-77.(1917) 
J.S.G.I.  58.  400  A. 

42.  Fischer  & Bigger  man , T.  Conversion  of  coal  and  similar 

substances  into  soluble  products  By  ozone. 

Ges.  Ahhandt  Zur  Kenntfflis  der  Kohle  I.  50-42. 

(1917) 

43.  Fischer,  F.  Extraction  of  coal  under  pressure  with 

solvents  other  than  Benzene. 

Ges.  Ahhandt  Zur  Kenntnis  der  Kohle  5,  2457  (1919) 

44.  Fischer,  F.  , & Gluud,  ?/.  Extraction  of  coal  with  dilute 

alkalies  at  nigh  temperatures. 

Ges.  Ahhandt  Zur  Kenntnis  der  Kohle  3,  243-5  (1919) 

45.  Pictet,  A.,  Researches  on  coal. 

Ann.  Chem  (9)  10  249-330  (1918) 


' 


-74. 

46.  Fischer,  F.  & Tropsch  Ozonization  of  coal  suspended  in 

a now  aquous  media. 

Ges  Ah hand t Zur  Eenntnis  der  Kohle  II  160  (1919) 

47.  Fischer,  F.  & Tropsch.  Hydrogenation  of  various  kinds 

of  coal. 

Ges  Ahhandt  Zur  Kenntnis  der  kohle  I 154-59  (1919) 
, 48.  Fischer,  F.  & Schrader.  The  origin  and  chemical  struct- 
ure of  coal. 

Brenstoff  Ghem  2 37-45  (1921) 

" " 213-9  (1921) 

G.  General. 

49.  Mineral  Industry  1920. 

50.  Hlaswetz  & Haberman.  Ann.  169  150  (1873) 


51. 

Eossel  Zeitz 

Physiol. 

Ghem. 

22  - 

176 

52. 

Eutscher  ” 

tt 

TT 

41  - 

407 

53. 

Emil  Fischer  n 

ii 

TT 

43  - 

151 

54.  Zelinsky,  I.  Ghem.  Ztg.  36.  824  (1914) 

55.  Kelley  Bui.  39  Hawaii  Agric.  Expt . Station  (1915) 

56.  Lathrop  Soil  Science  1,  509  (1916) 

57.  Hohart , F.B.  The  effect  of  carbon  dioxide  in  carboniz 

ation  processes. 

Univ.  of  111.  Thesis  (unpublished)  (1921) 

58.  Yliet,  E.  B.  , Trie  classification  of  coal. 

Univ.  of  111.  Thesis  1918. 


' 


— 


VITA 


The  writer  was  horn  in  Gape  Town,  Union  of  ^outh 
Africa  on  January  21,  1897.  He  attended  the  South  African 
College  High  School  during  the  years  1909 — 1914,  and  entered 
the  South  African  College,  now  the  University  of  Capetown, 
in  February  1915.  While  at  this  institution  he  was  enrolled 
as  a student  in  Liberal  Arts  and  Science  and  graduated  in 
Chemistry,  Physics  and  Mathematics  in  December  1917.  A year 
later  he  obtained  the  degree  of  master  of  Arts  in  Chemistry 
and  finally  spent  a year  as  graduate  assistant  in  that  de- 
partment. In  February  1920  he  entered  the  Graduate  School 
of  the  University  of  Illinois. 


I 


) 


